Absorbent article with multiple zone structural elastic-like film web extensible waist feature

ABSTRACT

Absorbent articles such as disposable diapers, incontinent briefs, diaper holders, training pants, feminine hygiene garments and the like, that have a unique waist feature that improves the dynamic fit as well as the containment characteristics of the absorbent article. Such absorbent articles comprise a chassis assembly preferably comprising a liquid pervious topsheet, a liquid impervious backsheet, and an absorbent core positioned between the topsheet and the backsheet; an extensible back waist feature; and a closure system for maintaining the absorbent article on the wearer. The extensible back waist feature provides an extensible feature that provides a more comfortable and contouring fit by initially conformably fitting the diaper to the wearer and by sustaining this fit. The extensible back waist feature has a hip panel, a central waistband panel, and a pair of side panels. The force/extension characteristics of each panel is designed to provide such improved fit and containment. While each panel of the extensible waist feature may be constructed from a number of extensible materials, the panels preferably comprise a structural elastic-like film web. The structural elastic-like film (SELF) web exhibits an elastic-like behavior in the direction of elongation without the use of added elastic materials. The configuration of the SELF web in each panel has specific characteristics to provide the desired force/extension characteristics of each panel.

This is a division of application Ser. No. 08/203,456, pending filed onFeb. 28, 1994.

FIELD OF THE INVENTION

The present invention relates to absorbent articles such as diapers,incontinent briefs, training pants, and the like, and more particularly,to absorbent articles having an extensible waist feature providingdynamic fit about the wearer as well as improved containmentcharacteristics of the absorbent article.

BACKGROUND OF THE INVENTION

Infants and other incontinent individuals wear absorbent articles suchas diapers to receive and contain urine and other body exudates.Absorbent articles function both to contain the discharged materials andto isolate these materials from the body of the wearer and from thewearer's garments and bed clothing. Disposable absorbent articles havingmany different basic designs are known to the art. For example, U.S.Pat. No. 26,152, entitled "Disposable Diaper" issued to Duncan and Bakeron Jan. 31, 1967, describes a disposable diaper which has achieved wideacceptance and commercial success. U.S. Pat. No. 3,860,003, entitled"Contractable Side Portions For Disposable Diaper", issued to Buell onJan. 14, 1975, describes an elasticized leg cuff disposable diaper whichhas achieved wide acceptance and commercial success.

However, absorbent articles have a tendency to sag or gap away from andto slide/slip down on the body of the wearer during wear. Thissagging/gapping and sliding/slipping is caused by the relative motionsof the wearer as the wearer breathes, moves and changes positions, bythe downward forces generated when the absorbent article is loaded withbody exudates, and by the fib-like element of the materials of theabsorbent article itself when subjected to such wearer's motions. Thissagging/gapping and sliding/slipping of the absorbent article can leadto premature leakage and poor fit of the absorbent article about thewearer in the waist regions and the leg regions of the absorbentarticle.

In order to more snugly fit absorbent articles about the wearer, certaincommercially available absorbent articles have been provided withelastic features. An example of a disposable diaper with elastic sidepanels is disclosed in U.S. Pat. No. 5,151,092, entitled "AbsorbentArticle With Dynamic Elastic Waist Feature Having Predisposed FlexuralHinge" issued to Buell, Clear, and Falcone on Sep. 22, 1992. However,elastics are costly and require a certain degree of manipulation andhandling during assembly. Further, while elastics do provide a degree ofstretch for the absorbent article, the components of the absorbentarticle to which the elastics are attached are typically not elasticsuch that the elastics must be prestretched prior to being secured tothe absorbent article or the inelastic components must be subjected tomechanical stretching (e.g., ring rolling) to enable the added elasticto be effective. Otherwise, the added elastic is restrained by theinelastic components.

Therefore, it is an object of the present invention to provide arelatively low cost, easy to manufacture, absorbent article havingsustained dynamic fit about the wearer during use.

It is a further object of the present invention to provide an absorbentarticle having a unique extensible waist feature, preferably without theuse of elastic, that provides sustained dynamic fit and improvedresistance to leakage during use due to the conformability of thematerials forming the waist feature by virtue of their readilyextensible nature.

It is a still further object of the present invention to provide anextensible waist feature on an absorbent article that exhibits an"elastic-like" behavior in the direction of applied force or elongationwithout the use of additional elastic material.

It is an even further object of the present invention to provide anextensible back. waist feature on an absorbent article that enhances fitand containment by providing multiple zones or panels having differentforced/extension properties to better distribute the forces encounteredby the back waist feature during use and provide the necessary stretchand extension characteristics in those zones.

These and other objects of the present invention will be more readilyapparent when considered in reference to the following description andwhen taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention provides absorbent articles such as disposablediapers, incontinent briefs, diaper holders, training pants, femininehygiene garments and the like, that have an extensible back waistfeature that improves the dynamic fit as well as the containmentcharacteristics of the absorbent article. Such absorbent articlescomprise a chassis assembly preferably comprising a liquid pervioustopsheet, a liquid impervious backsheet, and an absorbent corepositioned between the topsheet and the backsheet; an extensible backwaist feature having multiple panels or zones; and a closure system formaintaining the absorbent article on the wearer.

In a preferred embodiment of the present invention, the absorbentarticle has a T-shape comprising a chassis assembly and a extensibleback waist feature disposed in the back waist region. The extensibleback waist future provides an extensible member that provides a morecomfortable and contouring fit by initially conform ably fitting thediaper to the wearer and by sustaining this fit. The extensible backwaist feature further develops and maintains wearing forces (tensions)that enhance the tensions developed and maintained by the closuresystem. The extensible back waist feature further provides moreeffective application of the diaper. The extensible back waist featurehas a central waistband panel, a pair of side panels, and a hip panel.Each of the panels are designed to provide different force and extensionproperties to optimize the fit of the diaper. While each panel of theextensible back waist future may be constructed from a number ofextensible materials, they preferably each comprise a structuralelastic-like film (SELF) web since a SELF web allows the force/extensioncharacteristics to be specifically designed for each panel and with aminimum mount of materials (no conventional elastic materials need to beused).

A structural elastic-like film (SELF) web exhibits an elastic-likebehavior in the direction of elongation without the use of added elasticmaterials. SELF webs exhibit at least two significantly different stagesof controlled resistive force to elongation along at least onepredetermined axis when subjected to an applied elongation in adirection parallel to the predetermined axis. SELF webs include astrainable network having at least two contiguous, distinct, anddissimilar regions. One of the regions is configured so that it willexhibit resistive forces in response to the applied axial elongation ina direction parallel to the predetermined axis before a substantialportion of the other region develops significant resistive forces to theapplied elongation. At least one of the regions has a surface-pathlengthwhich is greater than that of the other region as measured substantiallyparallel to the predetermined axis while the material is in anuntensioned condition. The region exhibiting the longersurface-pathlength includes one or more fib-like elements which extendbeyond the plane of the other region. SELF webs exhibit first resistiveforces to the applied elongation until the elongation of the web issufficient to cause a substantial portion of the region having thelonger surface-pathlength to enter the plane of applied elongation,whereupon the SELF web exhibits second resistive forces to furtherelongation. The total resistive forces to elongation are higher than thefirst resistive forces to elongation provided by the first region.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as formingthe present invention, it is believed that the invention will be betterunderstood from the following description which is taken in conjunctionwith the accompanying drawings in which like designations are used todesignate substantially identical elements, and in which:

FIG. 1 is a plan view of a disposable diaper embodiment of the presentinvention having portions cut-away to reveal underlying structure, theouter surface of the diaper facing the viewer;

FIG. 1A is a simplified plan view of the disposable diaper embodiment ofFIG. 1 depicting the various panels of the diaper;

FIG. 2 is a cross-sectional view of the disposable diaper embodiment ofFIG. 1 taken through Line 2--2 in FIG. 1;

FIG. 3 is a plan view of the disposable diaper embodiment of FIG. 1 inits stretched condition with forces applied to the side panels;

FIG. 4 is a blown up plan view of a portion of the disposable diaper ofFIG. 1 showing the details of the SELF webs of the extensible back waistregion and the relative positioning of the elements of the diaper;

FIG. 5 is a plan view photograph of a preferred embodiment of a SELF webhaving a strainable network of the present invention with the rib-likeelements facing toward the viewer;

FIG. 5A is a segmented, perspective illustration of the SELF web of FIG.5 in an untensioned condition;

FIG. 5B is a segmented, perspective illustration of the SELF web of FIG.5 in a tensioned condition corresponding to stage I on theforce-elongation curve depicted in FIG. 6;

FIG. 5C is a segmented perspective illustration of the SELF web of FIG.5 in a tensioned condition corresponding to stage II on theforce-elongation curve depicted in FIG. 6;

FIG. 6 is a graph of the resistive force versus percent elongationcomparing the behavior of the SELF web of the present invention as shownin FIG. 5, with an otherwise identical, planar, base polymeric webmaterial;

FIG. 7 is a graph of the elastic hysteresis behavior of the SELF web ofFIG. 6 when subjected to 60% elongation and examined for hysteresisresponse;

FIG. 8 is a simplified side elevational view of a preferred apparatusused to form that portion of the SELF web of the present invention;

FIG. 9 is a plan view of the opposed meshing plates of the apparatus ofFIG. 8 laid side-by-side with their meshing surfaces exposed;

FIG. 10 is a simplified side elevational view of a static press used toform at least a portion of the base film into a SELF web of the presentinvention;

FIG. 11 is a simplified side elevational view of a continuous, dynamicpress used to form predetermined portions of the base film into a SELFweb of the present invention;

FIG. 12 is a simplified illustration of an apparatus used to form atleast a portion of a base film into a SELF web of the present invention;

FIG. 13 is a simplified illustration of yet another apparatus used toform at least a portion of a base film into a SELF web of the presentinvention;

FIG. 14 is a graph of the resistive force vs. percent elongationcomparing the behavior of an alternative SELF web material which is alaminate comprised of a layer of a polymeric film and a nonwoven layersecured by adhesive having a strainable network of the present inventionto the otherwise identical unformed, planar, base web material;

FIG. 15 is a graph of the elastic hysteresis behavior of the webmaterial having the strainable network of FIG. 14 when subjected to 60%percent elongation and examined for elastic hysteresis response;

FIG. 16 is a simplified plan view of an alternative disposable diaperembodiment of the present invention generally showing the direction ofextensibillity of the panels of the extensible back waist region;

FIG. 17 is a simplified close up plan view of an alternativeconfiguration of the side panel of the disposable diaper embodiment ofthe present invention;

FIG. 18 is a plan view of a still alternative disposable diaperembodiment of the present invention;

FIG. 19 is a plan view of the alternative disposable diaper embodimentof FIG. 18 showing the diaper in its stretched condition when forces areapplied to the side panels and to the front waist feature;

FIG. 20 is a partially cut-away plan view of an alternative disposablediaper embodiment of the present invention having an hourglass shape andan extensible front waist feature of a SELF web;

FIG. 21 is a fragmentary plan view of an alternative extensible frontwaist feature of the present invention;

FIG. 22 is a fragmentary plan view of a further alternative extensiblefront waist feature of the present invention;

FIG. 23 is a fragmentary plan view of a still further alternativeextensible front waist feature of the present invention; and

FIG. 24 is a fragmentary plan view of an even still further alternativeextensible front waist feature of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "absorbent article" refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term "disposable" is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A"unitary" absorbent article refers to absorbent articles which areformed of separate parts united together to form a coordinated entity sothat they do not require separate manipulative pans like a separateholder and liner. A preferred embodiment of an absorbent article of thepresent invention is the unitary disposable absorbent article, diaper20, shown in FIG. 1. As used herein, the term "diaper" refers to anabsorbent article generally worn by infants and incontinent persons thatis were about the lower torso of the wearer. It should be understood,however, that the present invention is also applicable to otherabsorbent articles such as incontinent briefs, training pants, femininehygiene garments, and the like.

FIG. 1 is a plan view of the diaper 20 of the present invention in itsflat-out, uncontracted state (i.e., with elastic induced contractionpulled out) with portions of the structure being cut-away to moreclearly show the construction of the diaper 20 and with the portion ofthe diaper 20 which faces away from the wearer, the outer surface,facing the viewer. As shown in FIG. 1, the diaper 20 has a generally"T-shape" and comprises a chassis assembly 22 preferably comprising aliquid pervious topsheet 24, a liquid impervious backsheet 26 joinedwith the topsheet 24, an absorbent core 28 positioned between thetopsheet 24 and the backsheet 26; extensible leg cuffs 30 eachcomprising a leg flap panel 31 and one or more elastic members, elasticstrands 54, operatively joined with the leg flap panel 31; an extensibleback waist feature 32 comprising a central waistband panel 34, a pair ofside panels 36, and a hip panel 38; a closure system for fastening thediaper on the wearer preferably comprising at least a pair of tape tabs40 and a landing member preferably comprising a reinforcing strip 41;and an extensible front waist feature 42 comprising a front waist panel43.

FIG. 1A shows a simplified plan view of the disposable diaper of FIG. 1depicting the various panels of the diaper 20 and their positioning withrespect to each other. The diaper 20 comprises a chassis assembly orchassis panel 22, a pair of leg flap panels 31, a front waist panel 43,a hip panel 38, a central waistband panel 34, and a pair of side panels36. The chassis panel or chassis assembly 22 is the main portion of thediaper from which the other panels emanate. The absorbent core isgenerally positioned within the chassis panel although it may extendinto other panels or zones of the diaper. A leg flap panel 31 extendsgenerally laterally outwardly from and along each longitudinal edge 23of the chassis panel 22. The leg flap panel 31 forms at least a portionof the leg cuff 30. As shown in FIG. 1A, the elastic strands 54 areoperatively joined to the leg flap panel 31 to form an extensible legcuff 30. The front waist panel 43 extends generally longitudinallyoutwardly from and along the lateral edge 23' of the chassis panel 22and preferably each leg flap panel 31 in the front waist region. Thefront waist panel 43 generally forms the extensible front waist featureof the diaper. The hip panel 38 extends generally longitudinallyoutwardly from and along the lateral edge 23' of the chassis panel 22and preferably each leg flap panel 31 in the back waist region. The hippanel 38 forms a portion of the extensible back waist feature. Thecentral waistband panel 34 extends generally longitudinally outwardlyfrom and along the hip panel 38. The central waistband panel 34 alsoforms a portion of the extensible back waist feature. The side panels 36each extend generally laterally outwardly from and along the centralwaistband panel 34 and at least a portion of the hip panel 38. The sidepanels 36 also form a portion of the back extensible waist feature.

As discussed hereinafter, each of the panels may be a separate memberjoined to the overall diaper structure or may be unitary with the diaperin that they comprise an extension of other elements of the diaper suchas the topsheet, the backsheet, or both. In the embodiment shown in FIG.1, all of the panels except for the side panels 36 comprise an extensionof the topsheet 24 and the backsheet 26. The side panels 36 comprise aseparate member joined to the central waistband panel 34 and at least aportion of the hip panel 38. Further, any or all of the panels may beextensible. The chassis panel 22 is typically not extensible in order tomaintain the integrity of the absorbent core 28 during use, although itmay be rendered extensible such as by being formed as a structuralelastic-like film (SELF) web as described herein. Preferably, theextensible panels comprise a SELF web. The use of a SELF web allows theforce/extension properties of each of the panels to be specificallydesigned to maximize the fit and containment of the diaper with aminimum amount of materials (no conventional elastic materials areneeded).

The diaper 20 of FIG. 1 has an inner surface (not shown), an outersurface 44 (facing the viewer in FIG. 1) opposed to the inner surface, afront waist region 45, a back waist region 46 opposed to the front waistregion 45, and a periphery which is defined by the outer edges of thediaper 20 in which the longitudinal edges are designated 47 and the endedges are designated 48. (While the skilled artisan will recognize thata diaper is usually described in terms of having a pair of waist regionsand a crotch region between the waist regions; in this application, forsimplicity of terminology, the diaper 20 is described as having onlywaist regions, each of the waist regions including a portion of thediaper which would typically be designated as part of the crotchregion). The inner surface of the diaper 20 comprises that portion ofthe diaper 20 which is positioned adjacent to the wearer's body duringuse (i.e., the inner surface generally is formed by at least a portionof the topsheet 24 and other components joined to the topsheet 24). Theouter surface 44 comprises that portion of the diaper 20 which ispositioned away from the wearer's body (i.e., the outer surface 44generally is formed by at least a portion of the backsheet 26 and othercomponents joined to the backsheet 26). The front waist region 45 andthe back waist region 46 extend, respectively, from the end edges 48 ofthe periphery to the lateral centerline 49 of the diaper 20. (Thelateral direction (x direction or width) is defined as the directionparallel to the lateral centerline 49 of the diaper 20; the longitudinaldirection (y direction or length) being defined as the directionparallel to the longitudinal centerline 50; and the axial direction (Zdirection or thickness) being defined as the direction extending throughthe thickness of the diaper 20.)

FIG. 1 shows a preferred embodiment of the diaper 20 in which thetopsheet 24 and the backsheet 26 have length and width dimensionsgenerally larger than those of the absorbent core 28. The topsheet 24and the backsheet 26 extend beyond the edges of the absorbent core 28 tothereby form certain of the panels and portions of the periphery of thediaper. The periphery defines the outer perimeter or, in other words,the edges of the diaper 20. The periphery comprises the longitudinaledges 47 and the end edges 48.

FIG. 2 is a cross-sectional view of the diaper embodiment of FIG. 1 ofthe present invention taken through line 2--2 of FIG. 1. FIG. 2 showsthe chassis assembly 22 comprising a portion of the top sheet 24, aportion of the backsheet 26, and the absorbent core 28 positionedbetween the topsheet 24 and the backsheet 26. In the embodiment shown inFIG. 2, the hip panel 38 is joined to and extends longitudinallyoutwardly from the chassis assembly 22, preferably from the waist edge56 of the absorbent core 28. The hip panel 38 is unitary with thechassis assembly 22 and comprises a structural elastic-like film (SELF)web comprising the portion of the topsheet and the backsheet extendinglongitudinally beyond the waist edge. Thus, the extensibility of the hippanel is achieved without the use of a separate elastic materialoperatively joined to the topsheet and the backsheet. The centralwaistband panel 34 is joined to and extends longitudinally outwardlyfrom the hip panel 38. The central waistband panel is unitary with thehip panel, and thus the chassis assembly in this embodiment, andcomprises a SELF web comprising the portion of the topsheet and thebacksheet. The bands 64' of the central waistband panel SELF web arepreferably wider (longitudinal dimension) than the bands 64" of the hippanel SELF web with the pleats 66' of the waistband panel SELF web beingpreferably wider than the pleats 66" of the hip panel SELF web. Thus,the extension forces of the central waistband panel SELF web are higherthan the extension forces of the hip panel SELF web.

The chassis assembly 22 (chassis panel) of the diaper 20 is shown inFIGS. 1 and 1A as comprising the main body (chassis) of the diaper 20.The chassis assembly 22 comprises at least an absorbent core 28,preferably an outer coveting layer comprising the topsheet 24 and thebacksheet 26. Thus, the chassis assembly 22 comprises the main structureof the diaper with other features added to form the composite diaperstructure. An exemplary example of a chassis assembly of the presentinvention is described in U.S. Pat. No. 3,860,003 issued to Kenneth B.Buell on Jan. 14, 1975, which patent is incorporated herein byreference.

The absorbent core 28 may be any absorbent means which is capable ofabsorbing and retaining liquids such as urine and other certain bodyexudates. The absorbent core 28 has a garment surface, a body surface,side edges 57, and waist edges 56. The absorbent core 28 may bemanufactured in a wide variety of sizes and shapes (e.g., rectangular,hourglass, "T"-shaped, asymmetric, etc.) and from a wide variety ofliquid-absorbent materials commonly used in disposable diapers and otherabsorbent articles such as comminuted wood pulp which is generallyreferred to as airfelt. Examples of other suitable absorbent materialsinclude creped cellulose wadding, meltblown polymers including coform,cross-linked cellulose fibers, tissue including tissue wraps o andtissue laminates, absorbent foams, absorbent sponges, superabsorbentpolymers, absorbent gelling materials, or any equivalent material orcombinations of materials. The configuration and construction of theabsorbent core may also be varied (e.g., the absorbent core may havevarying caliper zones, a hydrophilic gradient, a superabsorbentgradient, or lower average density and lower average basis weightacquisition zones; or may comprise one or more layers or structures).The total absorbent capacity of the absorbent core 28 should, however,be compatible with the design loading and the intended use of the diaper20. Further, the size and absorbent capacity of the absorbent core 28may be varied to accommodate wearers ranging from infants throughadults. FIG. 1 shows a preferred embodiment of the diaper 20 having arectangular-shape absorbent core.

An absorbent structure useful as the absorbent core 28 of the presentinvention that has achieved wide acceptance and commercial success isdescribed in U.S. Pat. No. 4,610,678 entitled "High-Density AbsorbentStructures" issued to Weisman and Goldman on Sep. 9, 1986. U.S. Pat. No.4,673,402 entitled "Absorbent Articles With Dual-Layered Cores" issuedto Weisman, Houghton, and Gellert on Jun. 16, 1987; U.S. Pat. No.4,888,231 entitled "Absorbent Core Having A Dusting Layer" issued toAngstadt on Dec. 19, 1989; U.S. Pat. No. 5,147,345 entitled "HighEfficiency Absorbent Articles For Incontinence Management", issued toYoung, LaVon & Taylor on Sep. 15, 1992; U.S. Pat. No. 5,102,597 entitled"Porous, Absorbent, Polymeric Macrostructures and Methods Of Making theSame", issued to Roe, Lahrman and Berg on Apr. 7, 1992; and U.S. Pat.No. 4,834,735, entitled "High Density Absorbent Members Having LowerDensity and Lower Basis Weight Acquisition Zones", issued to Alemany andBerg on May 30, 1989; also describe absorbent structures that are usefulin the present invention. The absorbent core 28 is preferably thedual-layer absorbent structure described in U.S. Pat. No. 5,234,423entitled "Absorbent Article With Elastic Waist Feature and EnhancedAbsorbency", issued to Alemany and Clear on Aug. 10, 1993. Each of thesepatents are incorporated herein by reference.

The backsheet 26 is positioned adjacent the garment surface of theabsorbent core 28 and is preferably joined thereto by attachment means(not shown) such as those well known in the art. For example, thebacksheet 26 may be secured to the absorbent core 28 by a uniformcontinuous layer of adhesive, a patterned layer of adhesive, or an arrayof separate lines, spirals, or spots of adhesive. Adhesives which havebeen found to be satisfactory are manufactured by H. B. Fuller Companyof St. Paul, Minn. and marketed as HL-1258. The attachment means willpreferably comprise an open pattern network of filaments of adhesive asis disclosed in U.S. Pat. No. 4,573,986 entitled "DisposableWaste-Containment Garment", which issued to Minetola and Tucker on Mar.4, 1986, and which is incorporated herein by reference. An exemplaryattachment means of an open pattern network of filaments comprisesseveral lines of adhesive filaments swirled into a spiral pattern suchas is illustrated by the apparatus and methods shown in U.S. Pat. No.3,911,173 issued to Sprague, Jr. on Oct. 7, 1975; U.S. Pat. No.4,785,996 issued to Ziecker, et al. on Nov. 22, 1978; and U.S. Pat. No.4,842,666 issued to Werenicz on Jun. 27, 1989. Each of these patents areincorporated herein by referent. Alternatively, the attachment means maycomprise heat bonds, pressure bonds, heat/pressure bonds, ultrasonicbonds, dynamic mechanical bonds, or any other suitable attachment meansor combinations of these attachment means as are known in the art.

The backsheet 26 is impervious to liquids (e.g., urine) and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term "flexible" refers to materials which are compliant and willreadily conform to the general shape and contours of the human body. Thebacksheet 26 prevents the exudates absorbed and contained in theabsorbent core 28 from wetting articles which contact the diaper 20 suchas bedsheets and undergarments. The backsheet 26 may thus comprise awoven or nonwoven material, polymeric films such as thermoplastic filmsof polyethylene or polypropylene, or composite materials such as afilm-coated nonwoven material. Preferably, the backsheet is athermoplastic film having a thickness of from about 0.012 mm (0.5 mil)to about 0.051 mm (2.0 mils). The backsheet preferably comprises apolyethylene blend film of about 0.025 mm (1.0 mil) as is manufacturedby Tredegar Corporation of Terre Haute, Ind. and marketed as P8863.

The topsheet 24 is positioned adjacent the body surface of the absorbentcore 28 and is preferably joined thereto and to the backsheet 26 byattachment means (not shown) such as those well known in the art.Suitable attachment means are described with respect to joining thebacksheet 26 to the absorbent core 28. As used herein, the term "joined"encompasses configurations whereby an element is directly secured to theother element by affixing the element directly to the other element, andconfigurations whereby the element is indirectly secured to the otherelement by affixing the element to an intermediate member(s) which inturn is affixed to the other element. In a preferred embodiment of thepresent invention, the topsheet 24 and the backsheet 26 are joineddirectly to each other in the diaper periphery and are indirectly joinedtogether by directly joining them to the absorbent core 28 by theattachment means (not shown).

The topsheet 24 is compliant, soft feeling, and non-irritating to thewearer's skin. Further, the topsheet 24 is liquid pervious permittingliquids (e.g., urine) to readily penetrate through its thickness. Asuitable topsheet may be manufactured from a wide range of materials,such as porous foams; reticulated foams; apertured plastic films; orwoven or nonwoven webs of natural fibers (e.g., wood or cotton fibers),synthetic fibers (e.g., polyester or polypropylene fibers), or acombination of natural and synthetic fibers. Preferably, the topsheet 24is made of a hydrophobic material to isolate the wearer's skin fromliquids which have passed through the topsheet and are contained in theabsorbent core 28 (i.e., to prevent rewet). If the topsheet is made of ahydrophobic material, at least the upper surface thereof is treated tobe hydrophilic so that liquids will transfer through the topsheet morerapidly. This diminishes the likelihood that body exudates will flow offthe topsheet rather than being drawn through the topsheet and beingabsorbed by the absorbent core. The topsheet can be rendered hydrophilicby treating it with a surfactant. Suitable methods for treating thetopsheet with a surfactant include spraying the material with thesurfactant and immersing the material in the surfactant. A more detaileddiscussion of such a treatment and hydrophilicity is contained in U.S.Pat. No. 4,988,344 entitled "Absorbent Articles With Multiple LayerAbsorbent Layers" issued to Reising, et al. on Jan. 29, 1991.

There are a number of manufacturing techniques which may be used tomanufacture the topsheet 24. For example, the topsheet 24 may be anonwoven web of fibers. When the topsheet comprises a nonwoven web, theweb may be spunbonded, carded, wet-laid, meltblown, hydroentangled,combinations of the above, or the like. A preferred topsheet is cardedand thermally bonded by means well known to those skilled in the fabricsart. A preferred topsheet comprises staple length polypropylene fibershaving a denier of about 2.2. As used herein, the term "staple lengthfibers" refers to those fibers having a length of at least about 15.9 mm(0.625 inches). Preferably, the topsheet has a basis weight from about18 to about 25 grams per square meter. A suitable topsheet ismanufactured by Veratec, Inc., a Division of International PaperCompany, of Walpole, Mass. under the designation P-8.

The diaper 20 preferably further comprises extensible leg cuffs 30 forproviding improved containment of liquids and other body exudates. Eachextensible leg cuff 30 may comprise several different embodiments forreducing the leakage of body exudates in the leg regions. (The leg cuffcan be and is sometimes also referred to as leg bands, leg flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003 entitled"Contractable Side Portions For a Disposable Diaper" issued to Buell onJan. 14, 1975, describes a disposable diaper which provides acontractible leg opening having a leg flap and one or more elasticmembers to provide an elasticized leg cuff (gasketing cuff). U.S. Pat.No. 4,909,803 entitled "Disposable Absorbent Article Having ElasticizedHaps" issued to Aziz & Blaney on Mar. 20, 1990, describes a disposablediaper having "stand-up" elasticized flaps (barrier cuffs) to improvethe containment of the leg regions. U.S. Pat. No. 4,695,278 entitled"Absorbent Article Having Dual Cuffs" issued to Lawson on Sep. 22, 1987,describes a disposable diaper having dual cuffs including a gasketingcuff and a barrier cuff U.S. Pat. No. 4,704,115 entitled "DisposableWaist Containment Garment" issued to Buell on Nov. 3, 1987, discloses adisposable diaper or incontinent garment having side-edge-leakage-guardgutters configured to contain free liquids within the garment. U.S. Pat.No. 5,032,120 entitled "Disposable Absorbent Article Having Improved LegCuffs" issued to Freeland & Allen on Jul. 16, 1991, discloses anabsorbent article having leg cuffs having a relatively low ultimatecontact force at relatively high elongations accomplished, for example,by low contact force differential material. U.S. Pat. No. 5,087,255entitled "Absorbent Article Having Inflected Barrier Cuffs" issued toSims on Feb. 11, 1992, discloses an absorbent article having inflectedbarrier cuffs with the distal edge positioned outboard of the proximaledge in one waist region and inboard in the other to provide better fitabout the hips/buttocks. Each of these patents are incorporated hereinby reference. While each extensible leg cuff 30 may be configured so asto be similar to any of the leg bands, leg flaps, barrier cuffs, orelastic cuffs described above, as shown in FIG. 1, each extensible legcuff 30 comprises the leg flap panel 31 extending laterally outwardlyfrom the chassis panel 22, the side edge 57 of the absorbent core 28,and one or more elastic members, elastic strands 54, operatively joinedwith the leg flap panel 31, such as is described in the above-referencedU.S. Pat. No. 3,860,003.

The diaper 20 further comprises extensible waist features that provideimproved fit and containment. The extensible waist features at leastextend longitudinally outwardly from the chassis assembly, preferably arespective waist edge of the absorbent core 28, and generally form atleast a portion of the end edge of the diaper 20. Thus, in theembodiment shown in FIG. 1, the extensible back waist feature 32comprises that portion of the diaper 20 extending from the waist edge 56of the absorbent core 28 in the back waist region 46 to the end edge 48of the diaper 20. While a disposable diaper of the present invention isconstructed with an extensible waist feature disposed in each waistregion (an extensible back waist feature 32 and an extensible frontwaist feature 42), the discussion will focus on diapers having differentconfigurations for each extensible waist feature. At a minimum, it ispreferred that the diaper at least have one of the extensible waistfeatures constructed according to the present invention, more preferablyat least the back extensible waist feature 32. The waist features can beconstructed as a separate element joined to the chassis assembly 22 oras an extension of other elements of the diaper (i.e., unitary). Thewaist features will be described with respect to preferred embodimentsin which certain portions or panels comprise an extension of otherelements of the diaper such as the backsheet 26, the topsheet 24, orboth, and other portions or panels comprise a separate element joined toother portions or panels of the waist feature or other panels of thediaper.

The extensible back waist feature 32 provides an extensible member thatprovides a more comfortable and contouring fit by initially conformablyfitting the diaper to the wearer and sustaining this fit throughout thetime of wear well past when the diaper has been loaded with exudatessince the extensible back waist feature allows the diaper to expand and,preferably, to contract. Further, the extensible back waist featuredevelops and maintains wearing forces (tensions) that enhance thetensions developed and maintained by the closure system to maintain thediaper on the wearer and that enhance the fit of the diaper about thewaist of the wearer. The extensible back waist feature further providesmore effective application of the diaper since even if the diapererpulls one side (side panel 36) of the extensible back waist featurefarther than the other during application (asymmetrically), the diaperwill "self-adjust" during wear.

As shown in FIG. 1, the extensible back waist feature 32 comprises acentral waistband panel 34; a pair of side panels 36; and a hip panel38. In the embodiment shown in FIG. 1, the hip panel 38 is disposedlongitudinally outwardly from the chassis assembly 22 (the chassispanel), preferably from the waist edge 56 of the absorbent core 28, inthe middle zone of the back waist region 46; the central waistband panel34 is disposed longitudinally outwardly from the hip panel 38; and theside panels 36 are each disposed laterally outwardly from the centralwaistband panel 34 and at least a portion of the hip panel 38. Asdiscussed hereinafter, the particular positioning of each panel of theback waist feature is important to the overall functioning of the backwaist feature. The term "panel" is used herein to denote an area orelement of the waist feature or diaper. (While a panel is typically adistinct area or element, a panel may overlap somewhat with an adjacentpanel.)

Each of the panels of the back waist feature 32 is extensible so as todynamically fit and conform to the wearer so as to provide such improvedfit and containment. The force/extension properties or characteristics(e.g., extension forces, available stretch (extension), and contractiveforce(s)) of each of the panels is specifically designed so as todynamically expand and move with the movements of the body of the weareradjacent that panel to enhance fit and containment. As discussedhereinafter, since each panel preferably comprises a SELF web asdisclosed hereinafter and has a specific and different function, theconfiguration of and materials comprising the SELF web of each panel arespecially selected to provide the different force and extensionrequirements of each panel, thus enhancing the functioning of diaper.

The hip panel 38 is joined to the chassis assembly 22 and is disposedlongitudinally between the central waistband panel 34 and the lateralcenterline 49, preferably the waist edge 56 of the absorbent core 28 asis shown in FIG. 1, and laterally between the side panels 36. The hippanel 38 is extensible in a direction having a vector component in thelateral direction, preferably in the lateral direction, to provide amore comfortable and contouring fit about the hips and buttocks of thewearer by initially conformably fitting the diaper to the hips/buttocksand sustaining this fit throughout the time of wear since the hip panelsallow portions of the diaper to expand with the body and return to itsoriginal configuration as the body moves. This additional extensibilityin the middle/back of the diaper allows the diaper to better wrap aroundthe wearer's hips and buttocks. As a result, the diaper fits better tothe body and reduces sagging, gapping and slippage. The hip panel isdesigned to have lower extension forces than the central waistbandpanel, and preferably the side panels, with higher extension capability,available stretch. This enables the diaper to fit wider at the hips thanin the central waistband panel, thus reducing the amount of materialthat is needed to construct the diaper to provide adequate fit andcoverage. Preferably, the extension force of the central waistband panelis at least about 2 times, more preferably between 2 to 20 times, mostpreferably between 5 to 10 times, greater than the extension force ofthe hip panel. (The extension force of the hip panel should be as low aspossible.) In a preferred embodiment, the extension force of the hippanel is less than about 10 g/cm, preferably less than about 5 g/cm, at50% extension. The hip panel 38, as shown in FIG. 3, thus flairs outafter the diaper is applied thereby directing the forces generated inthe side panels 36 to transfer to the central waistband panel 34. Thehip panel 38 also couples the elastic strands 54 with the waist closure.

The hip panel 38 may take on a number of different sizes and shapes. Forexample, the hip panel may have a trapezoidal, arcuate, or complexshape. As shown in FIG. 1A, the hip panel 38 preferably has arectangular shape to minimize material and processing costs. The size ofthe hip panel may also widely vary, depending upon its availablestretch, so long as it provides fit and containment at the hips. In apreferred embodiment of a large (8 kg to 14 kg) baby diaper, the hippanel may, for example, have a size typically about 65 mm long(longitudinal direction) and about 180 mm wide (lateral direction).

The hip panel 38 is extensible in at least one direction, preferably ina direction having a vector component in the lateral direction, morepreferably in the lateral direction, to provide better fit by providingextension that follows the hips/buttocks. It should be noted, however,that the hip panel may be extensible in any other direction or in morethan one direction. In addition, the hip panel may have one or morediscrete zones of extensibility. For example, in one embodiment, the hippanel may have a pair of extensible zones, each positioned laterallyoutwardly from a central nonextensible zone or panel. In the embodimentshown in FIGS. 1 and 4, the central zone is extensible while the lateralzones are nonextensible. Alternatively, the entire hip panel isextensible to provide the desired functions as described herein.

The hip panel 38 may be constructed in a number of configurations. Forexample, the hip panel can be constructed of any of the variouselastomeric materials or elastomeric laminates as are known in the art.An exemplary elastomeric material is a zero strain stretch laminate suchas described in above-referenced U.S. Pat. No. 5,151,092 (Buell, etal.). In an especially preferred embodiment, the hip panel comprises aSELF web as described hereinafter.

The hip panel 38 may comprise a separate element affixed to the chassispanel 22 and the side panels 36 and/or central waistband panel 34 or canbe constructed as an extension of other elements of the back waistfeature or the diaper such as the backsheet 26 or the topsheet 24,preferably both the topsheet and the backsheet. In the embodiment of thepresent invention shown in FIG. 1, the hip panel 38 comprises a portionof the topsheet 24 and a portion of the backsheet 26 formed into a SELFweb as described hereinafter.

The central waistband panel 34 is the primary component of theextensible back waist feature 32 that provides waist fit and appearance.(The central waistband panel can also be called the waistband or waistpanel of the back waist feature.) The central waistband panel 34 isjoined to the hip panel 38 and is disposed longitudinally outwardly fromthe hip panel 38 and laterally inwardly of the side panels 36 so as tofit in the upper back or lumbar zone of the wearer. The centralwaistband panel 34 is positioned toward the end edge 48 of the diaper 20to generally define the "central upper segment" of the back waistfeature, and preferably, such as is shown in FIG. 1, forms at least aportion of the end edge 48 of the diaper 20. Thus, the central waistbandpanel 34 provides a member that maintains a defined area coverage,contacts the wearer in the upper back or lumbar zone to snugly fit thewearer, and is extensible, preferably in a direction having a vectorcomponent in the lateral direction, more preferably in the lateraldirection, so as to dynamically move, fit, and conform to the wearer.The extension forces of the central waistband panel need to be high,generally higher than the hip panel and, preferably, higher than theside panels, in order to support the diaper without sagging,particularly after loading. (The extension force of the centralwaistband panel is preferably from about 1 to 2 about times as great asthe extension force of the side panels). The extension forces aretypically between about 10 g/cm to 30 g/cm, preferably between about 15g/cm and 20 g/cm, at 50% extension. The higher extension forces of thecentral waistband panel transfer the majority of forces generated in thefitting of the diaper in the side panels to the waist and upper hipregions of the wearer. This enables the diaper to fit higher on thewearer and to allow the tensional forces (a primary line of tension) tobe directed about the waist of the wearer, typically downward toward theabdominal crease of the wearer, so as to provide a continuous primaryline of tension to hold the diaper on the wearer. This higher fit andcontinuous line of tension maintains the sustained fit of the diaper.This higher fit also reduces skin marking at the legs and thighs of thewearer.

The central waistband panel 34 may have a number of different sizes andshapes. For example, the central waistband panel may have an arcuateshape so that forces transmitted through the central waistband panel arealong a line or zone disposed at an angle to the body of the wearer tofit the diaper into the lumbar curve of the back and to allow thetensional forces (the primary line of tension) to be directed downwardtoward the abdominal crease of the wearer so as to provide a continuousprimary line of tension. Examples of complex shapes useful for the shapeof the central waistband panel and the back waist feature are disclosedin U.S. patent application Ser. No. 08/044,562 entitled "Fitted Belt ForAbsorbent Garment" filed by New, et al. on Apr. 7, 1993, and U.S. patentapplication Ser. No. 08/072,300 entitled "Absorbent Articles ProvidingSustained Dynamic Fit" filed by LaVon, et at. on Jun. 3, 1993; which areincorporated herein by reference. In a preferred embodiment such as isshown in FIG. 1A, the central waistband panel 34 has a rectangularshape. The lateral width of the central waistband panel is typicallygreater than its longitudinal length. For a typical "large" (8 kg to 14kg) baby diaper, the central waistband panel may, for example, have asize of about 180 mm in the lateral direction by about 30 mm in thelongitudinal direction.

The central waistband panel 34 may be constructed in a number ofconfigurations and from a number of different materials. For example,the central waistband panel may be elasticized by operatively joining anelastic member thereto such as the elasticized waistbands known in theart and as are disclosed in U.S. Pat. No. 4,515,595 issued to Kievit, etal. on May 7, 1985; and U.S. Pat. No. 5,151,092 issued to Buell, et al.on Sep. 29, 1992; each of which are incorporated herein by reference.Thus, the central waistband panel may be a stretch laminate such as azero strain stretch laminate as is described in U.S. Pat. No. 5,151,092(Buell, et al.). In a preferred embodiment of the present invention, thecentral waistband panel comprises a SELF web as described s hereinafter.

The central waistband panel 34 may comprise a separate element affixedto the side panels 36 and/or the hip panel 38 or can be constructed asan extension of other elements of the back waist feature or the diapersuch as the backsheet 26 or the topsheet 24, preferably both thetopsheet and the backsheet. In the embodiment of the present inventionshown in FIG. 1, the central waistband panel 34 comprises a portion ofthe topsheet 24 and a portion of the backsheet 26 formed into a SELF webas described hereinafter.

The central waistband panel 34 is extensible in at least one direction,preferably in a direction having a vector component in the lateraldirection, more preferably in the lateral direction, to provide betterfit. It should be noted, however, that the central waistband panel maybe extensible in any other direction or in more than one direction. Inaddition, the central waistband panel may have one or more discretezones of extensibility. For example, as is shown in FIG. 4, the centralwaistband panel 34 may have a pair of non-extensible zones, eachpositioned laterally outwardly from a central extensible zone or panel.Alternatively, the entire central waistband panel can be extensible toprovide the desired functions as described herein.

The side panels 36 are those portions of the extensible back waistfeature 32 that extend laterally outwardly from the central waistbandpanel 34 and at least a portion of the hip panel 38. The side panels 36are each an extensible member that primarily function to provide a morecomfortable and contouring fit by initially conformably fitting thediaper to the wearer at application and sustaining this fit throughoutthe time of wear well past when the diaper has been loaded with exudatesby enlarging the circumference of the diaper at the sides, attaching theback waist region to the front waist region of the diaper to complete aclosure for the diaper, and distributing forces along both the waist andlegs to transfer these forces such that there is a snug fit with no skinirritation due to excessive forces on the legs or the waist. The sidepanels provide stretch as well as, in preferred embodiments, acontractive force after extension and application. Thus, the side panelsprovide a more comfortable and contouring fit by allowing the sides ofthe diaper to expand and contract. The side panels also develop andmaintain wearing forces (tensions) and enhance the tensions developedand maintained by the closure system to maintain the diaper on thewearer and enhance the fit. The side panels assist in maintaining theprimary line of tension formed by the primary fastening system; allowingthe diaper to conformably fit over the hips of the wearer where there isdynamic motion, and initially pretensioning the front extensible waistfeature, if provided on the diaper, since the diaperer typicallystretches the side panels when applying the diaper on the wearer so thatwhen the side panels contract, tension is transmitted from the sidepanels through the waist closure system into the extensible front waistfeature. The side panels further provide more effective application ofthe diaper since even if the diaperer pulls one side panel farther thanthe other during application, the diaper will "self-adjust" during wear.(While the extensible back waist feature has side panels; the extensiblefront waist feature may also have side panels, preferably extensibleside panels such as are described herein. )

The side panels 36 may have a number of different sizes and shapes. Forexample, the side panels may each have an arcuate shape so that forcestransmitted through the side panel are along a line or zone disposed atan angle to the body of the wearer to fit the diaper into the lumbarcurve of the back and to allow the tensional forces (the primary line oftension) to be directed downward toward the abdominal crease of thewearer so as to provide a continuous primary line of tension. Examplesof such side panels are described in U.S. patent application Ser. No.08/072,300 entitled "Absorbent Articles Providing Sustained Dynamic Fit"filed by LaVon, et al. on Jun. 3, 1993; and U.S. patent application Ser.No. 08/155,048 entitled "Absorbent Article With Multi-DirectionalExtensible Side Panels" filed by Robles, et al. on Nov. 19, 1993; eachof which is incorporated herein by reference. In the preferredembodiment shown in FIG. 1A, the side panels 36 have a rectangularshape. For a typical "large" (8 kg to 14 kg) baby diaper, the sidepanels may, for example, have a size of about 63 mm in the lateraldirection by about 57 mm in the longitudinal direction.

The side panels 36 may be constructed in a number of configurations andfrom a number of different materials. Examples of diapers withelasticized side panels are disclosed in U.S. Pat. No. 4,857,067 issuedto Wood, et al. on Aug. 15, 1987; U.S. Pat. No. 4,381,781 issued toSciaffara, et al. on May 3, 1983; U.S. Pat. No. 4,938,753 issued to VanGompel, et al. on Jul. 3, 1990; and the hereinbefore referenced U.S.Pat. No. 5,151,091 issued to Buell, et al. on Sep. 21, 1991; each ofwhich are incorporated herein by reference. Thus, the side panels maycomprise conventional elastic materials or mechanically stretchedlaminates such as a zero strain stretch laminate. In a preferredembodiment of the present invention, the side panels comprise a SELF webas described hereinafter.

The side panels 36 may comprise a separate element affixed to the backwaist feature 32 at the central waistband panel 34 and the hip panel 38,or can be constructed as an extension of other elements of the backwaist feature or the diaper such as the backsheet 26 or the topsheet 24,preferably both the topsheet and the backsheet. In the embodiment of thepresent invention shown in FIG. 1, the side panels 36 each comprise aseparate SELF web joined to the back waist feature (the centralwaistband panel 34 and the hip panel 38). The SELF web of the sidepanels, as described hereinafter, preferably comprises a laminate of twoor more layers, preferably two layers; most preferably a laminate of alayer of a polyethylene blend film such as is marketed by ClopayCorporation of Cincinnati, Ohio as Clopay 1401 and a nonwoven web suchas the P-8 material previously described for use as the topsheet. Theextension force of each side panel is preferably between about 10 g/cmto about 15 g/cm at 50% extension.

The side panels 36 are extensible in at least one direction, preferablyin a direction having a vector component in the lateral direction, morepreferably in the lateral direction, to provide better fit. It should benoted, however, that the side panels may be extensible in any otherdirection or in more than one direction. In addition, the side panelsmay have one or more discrete zones of extensibility. Preferably, eachentire side panel is extensible to provide the desired functions asdescribed herein.

While each panel of the back waist feature 32 may be constructed from anumber of different extensible or elastic materials as are known in theart, one or more, and preferably each, of the panels of the back waistfeature, for performance and cost reasons, is preferably constructed ofa structural elastic-like film (SELF) web. (The term "web" herein refersto a sheet-like material comprising a single layer of material or acomposite or a laminate of two or more layers. )

FIG. 5 shows an embodiment of a SELF web 52 (formed web material) of thepresent invention constructed of a single layer of a formed polymericmaterial. The SELF web 52 is shown in its substantially untensionedcondition. The web has two centerlines, a first centerline, l, (which isalso referred to as an axis, line, or direction "l") and a secondcenterline, t, (which is also referred to as an axis, line or direction"t") which is generally perpendicular to the first centerline. The webis comprised substantially of linear low density polyethylene (LLDPE)although it may also be comprised of other polyolefins such aspolyethylenes including low density polyethylene (LDPE), ultra lowdensity polyethylene (ULDPE), high density polyethylene (HDPE) orpolypropylene and/or blends thereof of the above and other materials.Examples of other suitable polymeric materials include, but are notlimited to, polyester, polyurethanes, compostable or biodegradablepolymers, and breathable polymers.

Referring to FIGS. 5 and 5A, the SELF web includes a "strainablenetwork" of distinct regions. As used herein, the term "strainablenetwork" refers to an interconnected and interrelated group of regionswhich are able to be extended to some useful degree in a predetermineddirection providing the SELF web with an elastic-like behavior inresponse to an applied and subsequently released elongation. Thestrainable network includes at least a first region 64 (also generallyreferred to herein as bands or channels) and a second region 66 (alsogenerally referred to herein as ribs or pleats). The SELF web 52 alsoincludes a transitional region 65 which is at the interface between thefirst region 64 and the second region 66. The transitional region 65will exhibit behavior of both the first region and the second region. Itis recognized that every embodiment of the present invention will have atransitional region, however preferred embodiments of the presentinvention will exhibit elastic-like behavior substantially as a resultof the first region 64 and the second region 66. Therefore, the ensuingdescription of the present invention will be concerned with the behaviorof the SELF web in the first regions and the second regions only and notthe complex behavior of the SELF web in the transitional regions.

SELF web 52 has a first surface and an opposing second surface. In thepreferred embodiment shown in FIGS. 5 and 5A, the strainable networkincludes a plurality of first regions 64 and a plurality of secondregions 66. The first regions 64 have a first axis 68 and a second axis69, wherein the first axis 68 is preferably longer than the second axis69. The first axis 68 of the first region 64 is substantially parallelto the first axis of the SELF web 52 while the second axis 69 issubstantially parallel to the second axis of the SELF web 52. The secondregions 66 have a first axis 70 and a second axis 71. The first axis 70is substantially parallel to the first axis of the SELF web 52, whilethe second axis 71 is substantially parallel to the second axis of theSELF web 52. In the preferred embodiment of FIG. 5, the first regions 64and the second regions 66 are substantially linear, extendingcontinuously in a direction substantially parallel to the first axis ofthe SELF web 52.

The first region 64 has an elastic modulus E1 and a cross-sectional areaA I. The second region 66 has an elastic modulus E2 and across-sectional area A2.

In the illustrated embodiment, the SELF web 52 has been "formed" suchthat the SELF web 52 exhibits a resistive force along a axis, which inthe case of the illustrated embodiment is substantially parallel to thefirst axis of the SELF web, when subjected to an applied axialelongation in a direction substantially parallel to the first axis. Asused herein, the term "formed" refers to the creation of a desiredstructure or geometry upon the SELF web that will substantially retainthe desired structure or geometry when it is not subjected to anyexternally applied elongations or forces. A SELF web of the presentinvention is comprised of at least a first region and a second region,wherein the first region is visually distinct from the second region. Asused herein, the term "visually distinct" refers to features of the SELFweb which are readily discernible to the normal naked eye when the SELFweb or objects embodying the SELF web are subjected to normal use. ASELF web of the present invention is comprised of a strainable networkof contiguous, "distinct", and "dissimilar" regions, wherein thestrainable network includes at least a first region and a second region,where the first region has a "surface-pathlength" less than that of thesecond region, as measured parallel to a predetermined axis when thematerial is in an untensioned state. As used herein, the term "formedportion" refers to the portion of the material which is comprised of thedesired structure or geometry of the strainable network. As used herein,the term "surface-pathlength" refers to a measurement along thetopographic surface of the region in question in a direction parallel tothe predetermined axis. As used herein, the term "distinct" or"dissimilar" when referring to regions, refers to regions within thestrainable network having measurably different surface-pathlengths asmeasured parallel to a predetermined axis while the SELF web is in anuntensioned condition. The method for determining the surface-pathlengthof the respective regions can be found in the test methods section setforth in subsequent portions of the specification.

Methods for forming materials include, but are not limited to, embossingby mating plates or rolls, thermoforming, high pressure hydraulicforming, or casting. While in embodiments as are shown in FIGS. 5 and 5Athe entire SELF web has been formed, the present invention may also bepracticed by forming only a portion thereof.

In the preferred embodiment shown in FIGS. 5 and 5 A, the first regions64 are substantially planar. That is, the material within the firstregion 64 is in substantially the same condition before and after theformation step undergone by the SELF web 52. The second regions 66include a plurality of rib-like elements 74. The rib-like elements maybe embossed, debossed or a combination thereof

The rib-like elements 74 have a first or major axis 76 which issubstantially parallel to the second axis of the SELF web and a secondor minor axis 77 which is substantially parallel to the first axis ofthe SELF web 52. The first axis 76 of the rib-like elements 74 is atleast equal to, and preferably longer than the second axis 77. Toenhance the two-stage resistive force versus elongation behaviorcharacteristics of the panels of the diaper of the present invention,the ratio of the first axis 76 to the second axis 77 is at least 1:1,preferably at least 2:1, or greater. In general, the greater this ratio,the more pronounced will be the two-stage resistive force versuselongation characteristic of the SELF web.

The first region 64 and the second region 66 each have a "projectedpathlength". As used herein, the term "projected pathlength" refers tothe length of a shadow of a region that would be thrown by parallellight. The projected pathlength of the first region 64 and the projectedpathlength of the second region 66 are equal to one another.

The first region 64 has a surface-pathlength, L1, less than thesurface-pathlength, L2, of the second region 66 as measuredtopographically in a direction parallel to the first axis of the SELFweb while the SELF web is in an untensioned condition. To enhance thetwo-stage resistive force versus elongation behavior characteristic ofthe SELF web having strainable networks of the present invention, thesurface-pathlength of the second region 66 is at least about 15 percentgreater than that of the first region, more preferably at least about 30percent greater than that of the first region, and most preferably atleast about 70 percent greater than that of the first region. Ingeneral, the greater the surface-pathlength of the second region, thegreater will be the elongation of the SELF web.

What makes the SELF web particularly well suited for use as the panelsof the diaper, and particularly the extensible back waist feature 32, isthat it exhibits a modified "Poisson lateral contraction effect"substantially less than that of an otherwise identical base web ofsimilar material composition. As used herein, the term "Poisson lateralcontraction effect" describes the lateral contraction behavior of amaterial which is being subjected to an applied elongation. The methodfor determining the Poisson lateral contraction effect of a material canbe found in the test methods section set forth in subsequent portions ofthe specification. Preferably, the Poisson lateral contraction effect ofthe SELF web of the present invention is less than about 0.4 when theweb is subjected to about 20 percent elongation. Preferably, the SELFweb exhibits a Poisson lateral contraction effect less than about 0.4when the SELF web is subjected to about 40, 50 or even 60 percentelongation. More preferably, the Poisson lateral contraction effect isless than about 0.3 when the SELF web is subjected to 20, 40, 50 or 60percent elongation. The Poisson lateral contraction effect of SELF websof the present invention is determined by the mount of the web materialwhich is occupied by the first and second regions, respectively. As thearea of the SELF web occupied by the first region increases, the Poissonlateral contraction effect also increases. Conversely, as the area ofthe SELF web occupied by the second region increases the Poisson lateralcontraction effect decreases. Preferably, the percent area of the SELFweb occupied by the first areas is from about 2% to about 90%, and morepreferably from about 5% to about 50%.

Web materials of the prior art which have at least one layer ofelastomeric film material will generally have a large Poisson lateralcontraction effect, i.e., they will "neck down" as they elongate inresponse to an applied force. SELF web materials of the presentinvention can be designed to moderate if not substantially eliminate thePoisson lateral contraction effect of film-based elastomeric webs of theprior art.

For the SELF web 52, the direction of applied axial elongation, D,indicated by arrows 80, in FIG. 5, is substantially perpendicular to thefirst axis 76 of the rib-like elements 74. As the rib-like elements 74are able to unbend or geometrically deform in a direction substantiallyperpendicular to their first axis 76, the direction of applied axialelongation to cause extension in the SELF web 52 is also substantiallyperpendicular to the first axis 76 of the rib-like elements 74.

While the direction of applied axial elongation D indicated by arrows 80is substantially perpendicular to the first axis 76 of the rib-likeelements 74, an applied axial elongation having a first axis componentwill cause the SELF web 52 to extend in the direction of applied axialelongation.

In FIG. 6 there is shown a graph of the resistive force-elongation curve720 of a formed polymeric SELF web of the present invention shown inFIG. 5 along with a curve 710 for a base film of similar composition.Specifically, the samples are polymeric web materials comprisedsubstantially of linear low density polyethylene, approximately 0.001inches thick, designated Sample 1401 available from Clopay ofCincinnati, Ohio. The method for generating the resistiveforce-elongation curves can be found in the test methods section setforth in subsequent portions of the specification. Referring now to theforce-elongation curve 720, there is an initial substantially linear,lower force versus elongation stage I designated 720a, a transition zonedesignated 720b, and a substantially linear stage II designated 720cwhich displays substantially higher force versus elongation behavior.

As seen in FIG. 6, a SELF web exhibits different elongation behavior inthe two stages when subjected to an applied elongation in a directionparallel to the first axis of the SELF web. The resistive force to theapplied elongation is significantly different between stage I (720a) andstage II (720c) of curve 720 as compared to curve 710 which does notexhibit this behavior. As seen in FIG. 6, the SELF web exhibitsdifferent elongation behavior in the two stages when subjected to anapplied elongation in a direction parallel to the first axis of the SELFweb. The resistive force exerted by the SELF web to the appliedelongation is significantly less in the stage I region (720a) versus thestage II region (720c) of curve 720. Furthermore, the resistive forceexerted by the SELF web to the applied elongation as depicted in stage I(720a) of curve 720 is significantly less than the resistive forceexerted by the base web as depicted in curve 710 within the limits ofelongation of stage I. As the SELF web is subjected to further appliedelongation and enters stage II (720c) the resistive force exerted by theSELF web increases and approaches the resistive force exerted by thebase web. The resistive force to the applied elongation for the stage Iregion (720a) of the SELF web is provided by the molecular-leveldeformation of the first region of the SELF web and the geometricdeformation of the second region of the SELF web. This is in contrast tothe resistive force to an applied elongation that is provided by thebase web depicted in curve 710 of FIG. 6, which results frommolecular-level deformation of the entire web. SELF web materials of thepresent invention can be designed to yield virtually any resistive forcein stage I which is less than that of the base web material by adjustingthe percentage of the web surface which is comprised of the first andsecond regions, respectively. The force-elongation behavior of stage Ican be controlled by adjusting the width, thickness, and spacing of thefirst region and the composition of the base web.

Referring now to FIG. 5B, as the SELF web is subjected to an appliedaxial elongation, D, indicated by arrows 80 in FIG. 5, the first region64 having the shorter surface-pathlength, L1, provides most of theinitial resistive force, P1, as a result of molecular-level deformation,to the applied elongation which corresponds to stage I. While in stageI, the rib-like elements 74 in the second region 66 are experiencinggeometric deformation, or unbending and offer minimal resistance to theapplied elongation. In the transition zone (720b) between stages I andII, the rib-like elements 74 are becoming aligned with the appliedelongation. That is, the second region is exhibiting a change fromgeometric deformation to molecular-level deformation. This is the onsetof a force wall. In stage II, as seen in FIG. 5C, the rib-like elements74 in the second region 66 have become substantially aligned with theplane of applied elongation (the second region has reached its limit ofgeometric deformation) and begin to resist further elongation viamolecular-level deformation. The second region 66 now contributes as aresult of molecular-level deformation in stage II a second resistiveforce, P2, to further elongation. The resistive forces to elongationprovide a total resistive force, PT, which is greater than the resistiveforce depicted in stage I. Accordingly, the general slope of theforce-elongation curve in stage II is significantly greater than thegeneral slope of the force-elongation curve in stage I.

The resistive force P1 is substantially greater than the resistive forceP2 when (L1+D) is less than L2. While (L1+D) is less than L2 the firstregion 64 provides an initial resistive force, P1, generally satisfyingthe equation: ##EQU1## When (L1+D) is greater than L2 the first andsecond regions provide a combined total resistive force, PT, to theapplied elongation, D, generally satisfying the equation: ##EQU2##

The maximum elongation occurring while in stage I is considered to bethe "available stretch" of the SELF web. The available stretchcorresponds to the distance over which the second region experiencesgeometric deformation. The available stretch can be effectivelydetermined by inspection of the force-elongation curve 720 as shown inFIG. 6. The approximate point at which there is an inflection in thetransition zone between stage I and stage II is the percent elongationpoint of "available stretch". The range of available stretch can bevaried from about 10% to 100% or more; this range of elongation is oftenfound to be of interest in disposable absorbent articles, and can belargely controlled by the extent to which surface-pathlength L2 in thesecond region 66 exceeds surface-pathlength L1 in the first region 64and the properties (composition) of the base film. The term availablestretch is not intended to apply a limit to the elongation which the webof the present invention may be subjected to as there are applicationswhere elongation beyond the available stretch is desirable.Significantly higher forces are required to achieve percent elongationsin the base film equivalent to those percent elongations in the SELF web52. The approximate extent of stage I can be controlled as desired byadjusting the pathlengths, L1 and L2, in an untensioned condition. Theforce-elongation behavior of stage I can be controlled by adjusting thewidth, thickness, and spacing of first region 64 and the properties ofthe base film.

The curve 730 and 735 in FIG. 7 depicts the elastic hysteresis behaviorexhibited by the SELF web of FIG. 5. The sample is the same as in FIG. 6(Clopay 1401). The sample was examined for elastic hysteresis behaviorat an elongation of 60%. Curve 730 represents the response to an appliedand released elongation during the first cycle and curve 735 representsthe response to applied and released elongation during the second cycle.The force relaxation during the first cycle 731 and the percent set 732are depicted in FIG. 7. Note that significant recoverable elongation, oruseful elasticity, is exhibited at relatively low forces over multiplecycles, i.e., this means the SELF web can easily expand and contract toa considerable degree. The method for generating the elastic hysteresisbehavior can be found in the test method section in the subsequentportion of the specification.

When the SELF web is subjected to an applied elongation, the SELF webexhibits an elastic-like behavior as it extends in the direction ofapplied elongation and retracts to its substantially untensionedcondition once the applied force is removed, unless extended beyond thepoint of yielding. The SELF web is able to undergo multiple cycles ofapplied elongation without losing its ability to substantially recover.Accordingly, the SELF web is able to return to its substantiallyuntensioned condition once the applied elongation or force is removed.

While the SELF web may be easily and reversibly extended in thedirection of applied axial elongation, in a direction substantiallyperpendicular to the first axis 76 of the rib-like elements 74, the SELFweb is not as easily extended in a direction substantially parallel tothe first axis of the rib-like elements. The formation of the rib-likeelements allows the rib-like elements to geometrically deform in adirection substantially perpendicular to the first or major axis of therib-like elements, while requiting substantially molecular-leveldeformation to extend in a direction substantially parallel to the firstaxis of the rib-like elements.

The amount of applied force required to extend the SELF web is dependentupon the composition and thickness of the base material forming the SELFweb and the width and spacing of the first regions, with narrower andmore widely spaced first regions requiring lower applied extensionforces to achieve the desired elongation for a given composition andthickness. The first axis 68, (i.e., the length) of the unreformedregions 64 is preferably greater than the second axis 69, (i.e., thewidth) with a preferred length to width ratio of about 5:1 or greater.

The depth and number of rib-like elements 74 can also be varied tocontrol the extension force and available stretch of the SELF web of thepresent invention. The available stretch or elongation is increased iffor a given a number of rib-like elements, the height or degree offormation imparted on the rib-like elements is increased. Similarly, theavailable stretch or elongation is increased if for a given height ordegree of formation, the number or frequency of rib-like elements isincreased.

There are several functional properties that can also be controlledthrough the application of the present invention. There is the resistiveforce exerted by the SELF web against an applied elongation, and theavailable stretch of the SELF web material before the force wall isencountered. The resistive force that is exerted by the SELF web againstan applied elongation is a function of the material composition andthickness and the percent of the projected surface area of the SELF webthat is occupied by the first region. The higher the percent areacoverage of the SELF web by the first region, the higher resistive forcethat the SELF web will exert against an applied elongation for a givenmaterial composition and thickness. The percent coverage of the SELF webby the first region is determined in pan if not wholly by the width ofthe first region and the spacing between adjacent first regions.

The available stretch of the SELF web is determined by thesurface-pathlength of the second region. This is determined at least inpart by the rib-like elements spacing, rib-like element frequency, anddepth of formation of the rib-like elements as measured perpendicular tothe plane of the SELF web. In general, the greater thesurface-pathlength of the second region, the greater the availablestretch of the SELF web.

While an entire SELF web of the present invention may include astrainable network of first and second regions, the present inventionmay also be practiced by providing only specific portions of the SELFweb with a strainable network comprised of first and second regions. Forexample, as shown in FIGS. 1 and 4, only portions of the centralwaistband panel and hip panel of the extensible back waist regioncomprise the SELF web. Portions of the central waistband panel and thehip panel also comprise the base laminate as described herein.

The configuration and spacing of the first and second regions may alsobe varied to vary the characteristics of the resultant SELF web. Forexample, the second regions may comprise curvilinear rib-like elements,the first regions and the second regions may be curvilinear, or thefirst regions may be curvilinear. The SELF web may also exhibit anelastic-like behavior along a plurality of axes by extending the axes ina radial, fan-like array to allow the SELF web to exhibit anelastic-like behavior along a plurality of axes. For example, themultiple axes may be positioned at various angles to one another such as45°, 90°, 135°, etc. In addition to the various angles of orientation,the regions themselves may be straight, curvilinear or combinationsthereof. The surface pathlengths in the second region may also provide adifference in amplitude of the rib-like elements such that the SELF webwill have different zones of available stretch. It is also possible thatthe rib-like elements can be varied between adjacent regions to providedifferent available stretches in the adjacent second regions. The widthsof the first region may also vary across the web with the narrowerregions offering a lower resistive force to an applied elongation ascompared to the higher resistive force offered by the wider firstregion.

The SELF web also need not be extensible only in the direction parallelto the lateral centerline of the diaper as is shown in FIG. 1. Forexample, the first axis and the second axis of the SELF web may bedisposed at an angle to the longitudinal centerline and lateralcenterline of the diaper 20, respectively. Thus, the SELF web wouldaxially elongate along a line at an angle to the lateral centerline ofthe diaper. This angle is preferably between about 0° and about 30° forthe diapers of the present invention. Further, portions of the SELF webmay have different angles of extensibility. For example, in the sidepanels, a portion of the side panel closest to the end edge of thediaper, the waist panel, may be extensible in a direction parallel tothe lateral centerline of the diaper; however, the portion of the SELFweb closest to the lateral centerline, the thigh panel, may have anextensibility nonparallel to the direction of extensibility of the waistpanel such that it is disposed at an angle to the lateral centerline.This multi-directional SELF panel can provide improved waist and leg

Referring now to FIG. 8, there is shown an apparatus 400 used to formthe SELF web 52 shown in FIG. 5. Apparatus 400 includes plates 401, 402.Plates 401, 402 include a plurality of intermeshing teeth 403, 404,respectively. Plates 401, 402 are brought together under pressure toform the base film 406.

Referring now to FIG. 9, it can be seen that plates 401 and 402 eachhave a first axis "1" and a second axis "t" which is substantiallyperpendicular to the first axis. Plate 401 includes toothed regions 407and grooved regions 408 both which extend substantially parallel to thefirst axis of the plate 401. Within toothed regions 407 of plate 401there are a plurality of teeth 403. Plate 402 includes teeth 404 whichmesh with teeth 403 of plate 401. When the base film 406 is formedbetween plates 401,402 the portions of the base film 406 which arepositioned within grooved regions 408 of plate 401 and teeth 404 onplate 402 remain undeformed. These regions correspond with the firstregions 64 of the SELF web 52 shown in FIG. 5. The portions of the basefilm 406 positioned between toothed regions 407 of plate 401 and teeth404 of plate 402 are incrementally and plastically formed creatingrib-like elements 74 in the second regions 66 of the SELF web 52.

The method of formation can be accomplished in a static mode, where onediscrete portion of a base film is deformed at a time. An example ofsuch a method is shown in FIG. 10. A static press indicated generally as415 includes an axially moveable plate or member 420 and a stationaryplate 422. Plates 401 and 402 are attached to members 420 and 422,respectively. While plates 401 and 402 are separated, base film 406 isintroduced between the plates, 401, 402. The plates are then broughttogether under a pressure indicated generally as "P". The upper plate401 is then lifted axially away from plate 402 allowing the formed SELFweb 408 to be removed from between plates 401 and 402.

FIG. 11 is an example of a continuous, dynamic press for intermittentlycontacting the moving web and forming the base material 406 into aformed web similar to the SELF web 52 of FIG. 5. Polymeric film 406 isfed between plates 401 and 402 in a direction generally indicated byarrow 430. Plate 401 is secured to a pair of rotatably mounted arms 432,434 which travel in a clockwise direction which move plate 401 in aclockwise motion. Plate 402 is connected to a pair of rotary arms 436,438 which travel in a counter clockwise direction moving plate 402 in acounter clockwise direction. Thus, as web 406 moves between plates 401and 402 in direction indicated by arrow 430, a portion of the base filmbetween the plates is formed and then released such that the plates 401and 402 may come back grab and form another section of base film 406.This method has the benefit of allowing virtually any pattern of anycomplexity to be formed in a continuous process, e.g., uni-directional,bidirectional, and multi-directional patterns.

The dynamic press of FIG. 11 could be used on a completed absorbentarticle to form strainable networks into the completed product. Forexample, the entire or portions of the completed absorbent article couldbe placed between plates 401 and 402 to create a strainable network inall layers of the absorbent article.

Another method of forming the base material into a SELF web is vacuumforming. An example of a vacuum forming method is disclosed in commonlyassigned U.S. Pat. No. 4,342,314, issued to Radel et al. on Aug. 3,1982. Alternatively, the SELF web of the present invention may behydraulically formed in accordance with the teachings of commonlyassigned U.S. Pat. No. 4,609,518 issued to Curro et al. on Sep. 2, 1986.Each of the above patents are being incorporated herein by reference.

In FIG. 12 there is shown another apparatus generally indicated as 500for forming the base film into a formed SELF web. Apparatus 500 includesa pair of rolls 502, 504. Roll 502 includes a plurality of toothedregions 506 and a plurality of grooved regions 508 that extendsubstantially parallel to an axis running through the center of thecylindrical roll 502. Toothed regions 506 include a plurality of teeth507. Roll 504 includes a plurality of teeth 510 which mesh with teeth507 on roll 502. As a base polymeric film is passed between intermeshingrolls 502 and 504, the grooved regions 508 will leave portions of thefilm unformed producing the first regions 64 of the SELF web 52. Theportions of the film passing between toothed regions 506 and teeth 510will be formed by teeth 507 and 510, respectively, producing rib-likeelements 74 in the second regions 66 of the SELF web 52.

Alternatively, roll 504 may consist of a soft rubber. As the base filmis passed between toothed roll 502 and rubber roll 504 the film ismechanically formed into the pattern provided by the toothed roll 502.The film within the grooved regions 508 will remain unformed, while thefilm within the toothed regions 506 will be formed producing rib-likeelements of the second region.

Referring now to FIG. 13, there is shown an alternative apparatusgenerally indicated as 550 for forming the base film into a SELF web inaccordance with the teachings of the present invention. Apparatus 550includes a pair of rolls 552, 554. Rolls 552 and 554 each have aplurality of toothed regions 556 and grooved regions 558 extending aboutthe circumference of rolls 552, 554 respectively. As the base filmpasses between rolls 552 and 554, the grooved regions 558 will leaveportions of the film unformed, while the portions of the film passingbetween toothed regions 556 will be formed producing rib-like elements74 in second regions 66.

While the SELF web has been described as a single base layer ofsubstantially planar polymeric film, the present invention may bepracticed equally well with other base materials or with laminates ofmaterials. Examples of base materials from which the SELF web of thepresent invention can be made include two-dimensional apertured filmsand macroscopically expanded, three-dimensional, apertured formed films.Examples of macroscopically expanded, three-dimensional, aperturedformed films are described in U.S. Pat. No. 3,929,135 issued to Thompsonon Dec. 30, 1975; U.S. Pat. No. 4,324,246 issued to Mullane, et al. onApr. 13, 1982; U.S. Pat. No. 4,342,314 issued to Radel, et al. on Aug.3, 1982; U.S. Pat. No. 4,463,045 issued to Ahr, et al. on Jul. 31, 1984;and U.S. Pat. No. 5,006,394 issued to Baird on Apr. 9, 1991. Each ofthese patents are incorporated herein by reference. Examples of othersuitable base materials include composite structures or laminates ofpolymer films, nonwovens, and polymer films and nonwovens. The laminatesof polymer films and nonwovens may also comprise absorbent or fibrousabsorbent materials, foams, or other compositions. Additionalreinforcing elements can also be added for strength and recoverybenefits.

Base materials comprising laminates of apertured films and nonwovenmaterials may also be used whereby in the process of forming suchmaterials, the connections between a plurality of the nonwoven fibersare broken up to protrude slightly through the apertures of theapertured film.

It may be desirable in certain embodiments to have the SELF web exhibita certain degree of bulkiness. Laminates of polymer films with high-loftnonwoven materials, and laminates with multi-layers of nonwovens areways of providing increased bulk. Other methods for creating bulkinclude the formation of a single layer of polymer film in the manner ofthis invention followed by prestretching of the film and subsequentapplication of the nonwoven to one or both sides while the polymer filmis in its prestretched condition. Upon relaxation of the stretch, thenonwoven material forms puckers which give the material added bulk.Another method for making bulky laminates is by forming individualpolymeric film layers in the manner of this invention, followed bylamination of multiple layers of these materials. Three dimensionallyapertured films that have been formed using the method described hereinalso provide good bulk in a laminate structure.

Other materials which may be subject to the deformation processesdisclosed herein for producing webs which exhibit an elastic-likebehavior in the direction of applied force include polymeric foams andthermally bonded air-laid fibrous structures.

FIG. 14 shows the force elongation behavior for a base web 830 and theformed SELF web 840 of the present invention wherein both webs arecomprised of a laminate of a layer of the Clopay 1401 polyethylene blendfilm of FIG. 6 adhered via hot melt glue available from FindleyAdhesives, of Wauwautosa, Wis., Sample 2301, to a layer of nonwovenmaterial made substantially of polypropylene fibers as is available fromVeratec of Walpole, Mass., under the designation P-11. Referring now tocurve 840, there is an initial substantially linear, lowerforce-elongation stage I designated 840A, a transition zone designated840B, and substantially linear stage 1I designated 840C. For thislaminate web, note the distinctive lower force 2-stage behavior of theformed SELF web as compared to the base web. The curves 850 and 855 inFIG. 15 show the hysteresis behavior of the same type when examined at60% elongation. Curve 850 represents the response to applied elongationduring the first cycle and curve 855 represents the response to appliedelongation during the second cycle. The force elongation during thefirst cycle 851 and the percent set 852 are depicted in FIG. 15. Notethat this laminate web exhibits a very significant elastic recovery overthe observed range of elongation.

In a preferred embodiment of the present invention, the SELF webcomprises a laminate of two layers comprising an inner layer 53 and anouter layer 55. The inner layer 53 is preferably a nonwoven materialsuch as the P-8 material previously described. The outer layer 55 ispreferably the base polymeric film as described herein with reference toFIG. 5 (Clopay 1401) or the backsheet (Tredegar P8863). Alternatively, asupport layer may be added to provide a three layer laminate. Further, anonwoven layer may be added over the outer layer to provide a softerfeel for the outside of the waist feature. The laminates may be combinedby any of a number of bonding methods known to those skilled in the art.Such bonding methods include but are not limited to thermal bonding;adhesive bonding (using any of a number of adhesives including but notlimited to spray adhesives, hot melt adhesives, latex based adhesivesand the like); sonic bonding; and extrusion laminating whereby apolymeric film is east directly onto a nonwoven substrate, and whilestill in a partially molten state, bonds to one side of the nonwoven orwhere a meltblown nonwoven is directly attached to a polymeric web.

FIG. 4 shows a blown up plan view of the diaper of the present inventionshowing the specific design of the SELF webs forming the diaper and therelative positioning of each of the panels and other elements formingthe diaper. As discussed hereinabove, the width (longitudinal dimensionin FIG. 1) of the bands (the channels or first regions) of the SELF webis used to control the extension forces and the available stretch of theresultant SELF web. In the preferred embodiment shown in FIG. 4, thecentral waistband panel 34 has four bands 64' of 3 mm width each. Thereare also three pleats 66' spaced at a width of 6.35 min. Thus, thecentral waistband panel has an extension force at 50% extension of about17 g/cm. The available stretch of the central waistband panel is about60%. The preferred side panels 36 comprise a SELF web having an equal toor lower extension force and higher available stretch than the centralwaistband panel 34. The side panels 36 each preferably comprise sevenbands 64'" of 3 mm width and six pleats 66'" spaced at a width of 5.6 mmThe side panels thus each have a force/extension characteristic at a 50%extension of about 13 g/cm. The available stretch of each side panel isabout 110%. The side panels have different force/extension propertiesfrom the central waistband panel, despite the fact that the bands arethe same, due to the difference in properties of the base materials andthe width of the pleats. (One of the layers of the side panel is theClopay 1401 polyethylene film while the one of the layers of the centralwaistband panel is the Tredegar P8863 polyethylene film.) The hip panel38 comprises a SELF web designed to provide seven bands 64" of 1 mmwidth and eight pleats 66" of 6.35 mm width. The hip panel thus has anextension force at 50% extension of about 3 g/cm. The available stretchof the hip panel is about 60%. Thus, the hip panels preferably haveforce/extension properties less than the side panels and less than thecentral waistband panel; however, the amount of extension of the hipspanel is greater than the central waistband panel. The extension forcesof the hip panel are less than that of the central waistband panel dueto the width of the bands.

With the force/extension characteristics providing extension asdescribed above, it has also been found that the positional relationshipbetween certain elements of the extensible back waist feature and/or thediaper further enhance the fit and containment of the diaper.

It has been found that the side panels 36 should be joined to not onlythe central waistband panel 34 but also to at least a portion of the hippanel 38. This configuration allows forces generated in the side panelsby fitting the diaper on the wearer to be transmitted not only throughthe central waistband panel but also the portion of the hip paneladjacent the central waistband panel. The hip panel thus extends toaccommodate forces distributed in the central waistband panel causingless strain and stress on the diaper and expands with the forces in theside panels to better accommodate the hips and buttocks of the wearerwhile providing additional extensibility to accommodate furthermovements of the hips and buttocks as the wearer moves, walks, stands,etc. While the side panels may be disposed so as to be longitudinallyaligned with the entire hip panel, it is preferred that the side panelsare longitudinally aligned with only a portion of the hip panel so thata continuous line of force through the waistband is provided and inorder to maximize expansion of the lower back side of the hip panel. Itis preferred that the side panel overlap with the hip panels from 10% toabout 90%, more preferably from about 40% to about 60% of the length(longitudinal dimension) of the total length of the side panel. In theembodiment shown in FIG. 1, the side panels overlap with the hip panelabout 27 mm with the hip panels extending beyond the side panels fromabout 13 mm to about 43 mm, preferably about 28 mm.

As shown in FIG. 4, the side panel 36 is preferably joined to anonextensible portion of both the central waistband panel 34 and the hippanel 38. This nonextensible portion, bridging element 58, allows forcesgenerated in the side panels 36 during application and use of the diaperto be "diffused" or spread out to more evenly distribute the forces inthe central waistband panel 34 and the hip panel 38. While the sidepanel 36 could be joined to an extensible portion or be constructed asunitary with the SELF webs of the central waistband panel and the hippanel, such a construction allows direct force transfer through specificsites thereby concentrating the forces and stresses rather than allowingthem to be distributed over a wider area. The side panels can be joinedto the panels, preferably the bridging element 58, in a number ofdifferent ways as are known in the an and previously discussed herein,including by adhesives, heat/pressure bonds ultrasonic bonding ormechanical bonding. The side panels are preferably bonded to the otherpanels via mechanical bonding.

It has also been found that the positioning of the operative ends 55 ofthe leg elastics (elastic strands 54) with respect to the leg edge 37 ofthe side panel 36 is an important parameter in optimizing fit about theleg of the wearer. While the elastic strands 54 may be any lengthconsistent with providing a leg cuff, it has been found that theoperative ends 55 of the elastic strands 54 preferably extend to the legedge 37 of the side panels 36 to eliminate the possibility of leggapping and the resultant leakage at the back of the legs. (The term,"operative ends", as used herein means the point where the elasticstrand is operatively joined to the leg flap panel and contracts orgathers the leg flap panel. Thus, unadhered segments of the elasticstrands may extend beyond the zones defined herein since they do not acton the diaper or perform a contractive or gathering function.) Leakageand gapping at the back of the legs is improved when the elastic strands54 extend beyond the waist edge 56 of the absorbent core 28 into the hippanel 38 because the elastic strands tend to curve with the extension ofthe hip panel and better fit around the buttocks of the wearer. (SeeFIG. 3.) The position of the operative ends 55 of the elastic strands 54in the hip panel 38 also couples the leg closure and leg fit with thecentral waistband panel 34 and side panels 36 to provide a continuousclosure and line of force about the legs. Thus, it has been found thatthe operative ends of the elastic strands should extend to at least thehip panels, preferably into the hip panels, and more preferably to aboutthe leg edge of the side panels, most preferably within about 10 mm ineither direction from the leg edge.

The positioning of the absorbent core 28 may also affect the performanceof the diaper and the back waist feature. Since the absorbent core isrelatively nonextensible, positioning the absorbent core in anextensible feature can degrade the integrity of the core during use,especially when wet, and can restrict the extension of the panel. Thus,as shown in FIG. 1, the absorbent core 28 does not extend into the hippanel 38. However, the absorbent core may extend into the hip panel ifmore absorbent capacity is needed or a stiffener is required. If theabsorbent core extends into the hip panel, it is preferable to eithernot make that portion of the hip panel extensible or not join thatportion of the absorbent core to the extensible panel, thus allowing theabsorbent core to "float" and not restrict the extension of the hippanel.

FIG. 3 shows the diaper of FIG. 1 in a fiat configuration approximatingthe forces applied to the extensible back waist feature 32 during wear.As can be seen from the drawing, the side panels 36 extend such thattheir waist edge 37' is extended more than the leg edge 37 (about 80 mmversus 75 mm) such that more of the forces through the side panels areresolved adjacent the waist edge 37' (the end edge 48 of the diaper 20).The central waistband panel 34 has also been extended (to about 250 mm)with the majority of the forces resolved through the central waistbandpanel. The hip panel 38 has been extended with more extension adjacentits upper edge than its lower edge. However, this extension allows thehip panel to better wrap the hips and buttocks of the wearer resultingin better fit and improved containment at the hips. The elastic strands54 of the leg cuffs 30 are shown to curve in the hip panels 38 toprovide a cuff that better conforms to the buttocks of the wearer. (Itshould be noted that if the leg cuff comprises a barrier cuff as isdescribed in the above-referenced U.S. Pat. No. 4,695,278 (Lawson), thebarrier cuff will also curve in the same manner and provide better fit Sabout the buttocks.)

As shown in FIG. 1, the diaper 20 may also be provided with anextensible front waist feature 42. The extensible front waist feature 42is designed to fit around the abdomen in the front waist of the wearerto improve the fit and containment of the diaper at the front waist. Theextensible front waist feature 42 is positioned in the front waist panel43 and extends longitudinally outwardly from the chassis assembly 22,preferably the waist edge 56 of the absorbent core 28, and generallyforms at least a portion of the end edge 48 of the diaper 20 in thefront waist region 45. The extensible front waist feature 42 maycomprise any of the known configurations of an elastic feature or any ofthe extensible features as described herein. For example, the extensiblefront waist feature may comprise any of the elasticized waistbands asare known in the art such as are disclosed in the above-referenced U.S.Pat. No. 4,515,595 (Kievit, et al.) and U.S. Pat. No. 5,151,092 (Buell,et al.). Further, the extensible front waist feature may comprise astretch laminate such as a zero strain stretch laminate as is describedin U.S. Pat. No. 5,151,092 (Buell, et al.). Examples of alternativeextensible front waist features are described herein with respect to thealternative embodiments. In an especially preferred embodiment of thepresent invention as is shown in FIG. 1, the front waist panel 43comprises a SELF web. The SELF web of the front waist panel preferablyhas the same or similar force/extension characteristics as the SELF webof any of the other panels of the diaper, including, for example, thecentral waistband panel, the hip panel, or the side panel. However, theSELF web of the front waist panel may also be designed to have its ownunique force/extension characteristics. In a preferred embodiment for alarge (8 kg to 14 kg) baby diaper, the front waist panel has alongitudinal dimension of about 15 mm and a lateral dimension of about180 mm. The extension force of the front waist panel is preferablygreater than or equal to the extension force of the central waistbandpanel. The SELF web of the front waist panel is preferably designed tohave three bands of 3 mm width and 2 pleats of 6.35 mm width to providean extension force at 50% extension of 26 g/cm with an available stretchof 60%.

The diaper 20 is also provided with a closure system for fining thediaper on the wearer. While the closure system may take on a number ofconfigurations such as adhesive tape tabs, mechanical closure tape tabs,fixed position fasteners, side seams as for training pants, or any otherclosure means as are known in the art; as shown in FIG. 1, the closuresystem preferably comprises an adhesive tape tab fastening systemincluding a pair of tape tabs 40 and a landing member, preferably areinforcing strip 41 as in FIG. 1 or, the alternative, a portion of thebacksheet, positioned in the front waist region 45 of the diaper 20.Examples of suitable adhesive tape tab fastening systems are disclosedin U.S. Pat. No. 3,848,594 issued to Buell on Nov. 19, 1974; and U.S.Pat. No. 4,662,875 issued to Hirotsu and Robertson on May 5, 1987; eachof which are incorporated herein by reference. Examples of other closuresystems, including mechanical closure systems, useful in the presentinvention, are disclosed in U.S. Pat. No. 4,869,724 issued to Scripps onSep. 26, 1989; U.S. Pat. No. 4,848,815 issued to Scripps on Jul. 11,1989; and the two-point fastening system described in U.S. Pat. No.5,242,436 issued to Well, Buell, Clear, and Falcone on Sep. 7, 1993;each of which are incorporated herein by reference. When a two-pointfastening system is used, the waist closure members of the waist closuresystem are preferably longitudinally aligned with the extensible frontwaist feature and laterally aligned with the elastic strands of theextensible leg cuff to provide an effective closure about both the legsand the waist.

In an alternative embodiment of the present invention, the diaper mayalso be provided with ear flap panels that extend laterally outwardlyfrom the chassis assembly and the front waist panel. The ear flap panelsprovide a structure to which the waist feature can be attached toencircle the legs and waist of the wearer. The ear flap panels may takeon a number of different sizes, shapes, configurations, and materials.The ear flap panels may comprise a portion of the material(s) making upone or more of the diaper elements, including the topsheet and thebacksheet. Alternatively, the ear flap panels may comprise a separateelement or a plurality of elements affixed to the diaper. Suitablematerials for use as the ear flap panels include woven webs; nonwovenwebs; films, including polymeric films; foams; laminate materialsincluding film laminates, nonwoven laminates, or zero strain laminates;elastomers; composites; SELF webs; or any combination of thesematerials. The ear flap panels may be joined to the chassis assembly byany means as are known in the art; for example, the ear flaps may becontinuously or intermittently bonded to the chassis assembly usingheated or unheated adhesive, heat bonding, pressure bonding, ultrasonicbonding, dynamic mechanical bonding, or any other method that is knownin the art.

The diaper 20 is preferably applied to a wearer by positioning the backwaist region 46 under the wearer's back and drawing the remainder of thediaper between the wearer's legs so that the front waist region 45 ispositioned across the front of the wearer. The tab portions of the tapetabs 40 are then released from the release portion. The diaperer thenwraps the side panel 36 around the wearer, while still grasping the tabportion. The side panel will typically be extended and tensioned duringthis operation so as to conform to the size and shape of the wearer. Thetape tab 40 is secured to the reinforcing strip 41, the landing member,on the chassis assembly 22 to effect a side closure. The process is thenrepeated with the other tape tab. Thus, the diaper is closed on thewearer and the extensible back waist feature and the other elements, ifprovided, provide the fit and containment benefits as described herein.

Alternatively, the diaper may be provided with a closure system thatallows the side panels to be first joined together. The diaperer thenbrings the chassis assembly between the legs of the wearer and joins thechassis assembly to the outer layer of the waist feature. Such aconfiguration and securing method is more fully described in theabove-referenced U.S. application Ser. No. 08/044,562 (New, et al.).

FIG. 16 is a simplified plan view of an alternative disposable diaper1620 of the present invention wherein the hip panel 1638 has a multiplezone SELF web o construction. (The particular construction of the SELFweb has been simplified by showing the bands making up the SELF web.)The hip panel 1638 has three zones: a central zone 1600 and two legzones 1602. The SELF web of each leg zone 1602 preferably has the firstand second regions disposed at an angle to the lateral direction so thatextensibility is provided at an angle to the lateral direction. Lateralforces developed in the side panels 36 are directed along a line at anangle to the lateral direction through the hip panels 1638 to moreconformably fit about the buttocks of the wearer. The SELF web of thecentral zone 1600 is similar to the SELF web pattern of the hip panel 38shown in FIG. 1. The central zone 1600 provides lateral extensibilityadjacent the central waistband panel 34. In the embodiment shown in FIG.16, the central zone 1600 has a higher extension force than the legzones 1602 (lower extension/available stretch), preferably even highthan the central waistband panel 34, to provide snug fit by holding thediaper in place without roll-over or "pooching" out. The central zone1600 may even provide no extensibility (i.e., nonextensible), ifdesired.

It is preferred, however, in some embodiments, that the extension forcesof the central zone be less than or equal to the lateral vectorcomponent of the extension forces of the leg zones, particularly when abarrier cuff is used for the leg cuff.) This configuration of the hippanel better distributes forces in both the legs and the buttocks regionby allowing extensibility both in the lateral and longitudinal directionin the leg zone. When the leg cuff of the diaper comprises a barriercuff such as is described in U.S. Pat. No. 4,695,278 (Lawson), the hippanel may also comprise a central zone and a pair of leg zones. The sideedges of the central zone are positioned inward from the proximal edgesof the barrier cuffs. Such a proximal edge is positioned in each legzone. The extension force of the central zone is preferably less thanthe extension force of the leg zone to anchor each barrier cuff whileproviding extensibility for the hip panel.

FIG. 17 shows an alternative embodiment of a side panel 1736 of the backwaist feature 32 wherein the side panel 1736 has a multiple zone SELFweb construction. The portion of the side panel 1736 adjacent the endedge 48 of the diaper and in alignment with the central waistband panel34, the waist zone 1700, comprises a first SELF web that providesdistribution of the extension forces and extension in a first directionhaving a vector component in the lateral direction, preferably thelateral direction. The side panels 1736 also have a leg zone 1702adjacent the leg edge 37 of the side panel 1736 that comprises a secondSELF web having a pattern of bands and pleats providing force resolutionand extensibility in a second direction different from the firstdirection, preferably at an angle to the lateral direction. This seconddirection of extension provides better fit about the wearer bydistributing the forces at an angle in the leg zone 1702. It should alsobe noted that while the embodiment of FIG. 17 shows the side panel asone continuous member, the side panel can also be constructed from twoseparate SELF webs joined together to form a two by two side panel suchas is disclosed in the above-referenced U.S. patent application08/155,048 (Robles, et al.), hereby incorporated herein by reference.

FIG. 18 shows an alternative disposable diaper 1820 of the presentinvention wherein the leg flap panels 1831 further comprise a SELF weband the front waistband panel 1842 is a multiple zone SELF web. The SELFweb of the leg flap panels provides extensibility in the lateraldirection. By providing a SELF web leg cuff next to, over, or outside ofthe elastic strands 54, the diaper 1820 has an area adjacent the legswhich can expand when needed for additional void volume due to heavyloading, and also to provide a snug fit to reduce the possibility ofleakage in the leg regions due to gapping. As the diaper is loaded andgets heavier, the weight forces cause the extensible leg flap panels1831 to expand in the lateral direction thereby reducing gapping at thelegs due to this expansion instead of the cuff being pulled downward bythe weight and gapping away from the leg. The result is that action ofthe leg cuff 30 is independent from the absorbent core 28 thus providingbetter fit and containment. Additionally, the SELF s web enhances thesoftness of the product in the leg cuff and contributes to overall babyfriendly aesthetics. In fact, the entire diaper, including the chassispanel 22, may, if desired, comprise a SELF web to provide softness andcontainment characteristics. In the embodiment shown in FIG. 18, theSELF web of the leg flap panels 1831 has 75 bands of 1 mm width and 74pleats of 6.35 mm width each. The leg flap panel thus has an extensionforce at 50% extension of 6 g/cm and an available stretch of 60%. Theelastic strands 54 are operatively joined in the leg flap panel toprovide an extension force of 60 g at 85% extension. (It has been foundthat the SELF web should preferably have an extension force no greaterthan 1/2 of, preferably between about 1/5 to about 1/10 of, theextension force of the elastic strands 54. Since the elastic strands 54are s preferably operatively joined to the leg flap panel 1831 toprovide an extension force between about 50 and about 60 g then theextension forces of the leg flap panels are preferably less than 30g/cm, more preferably less than 20 g/cm, and most preferably less than10 g/cm, at 50% extension. These extension force characteristics providethe improvements in gapping and containment described herein.

The front waist panel 1832 has multiple zones: a central waistband zone1800 and a rummy zone 1802. The central waistband zone 1800 provides thefunction of the front waist feature as previously described herein. Thetummy zone 1802 provides extension about the belly of the wearer whichtypically expands and contracts during use. Thus, the tummy zone 1802moves with the stomach of the wearer and reduces the tendency s of thefront waist to sag and gap during use. The extension forces of theoverall front waist panel 1843 are preferably less than the extensionforce of the central waistband panel 34 of the back waist feature 32 toallow the front to "flair" out. The extension force of the front waistpanel 1843 is preferably between about 5 g/cm and 15 g/cm at 50%extension. In an alternative embodiment, the extension force of therummy zone 1802 may be less than or equal to the extension force of thecentral waistband zone 1800 to allow more extension in the tummy panelto accommodate the wearer's stomach and to provide a line of tension inthe central waistband zone that more snugly fits the wearer. (In analternative embodiment, this diaper may also be provided with the twopoint fastening system described in U.S. Pat. No. 5,242,436 (Weil, etal.) to further enhance the fit of the diaper.)

FIG. 19 shows the diaper of FIG. 18 in a flat configurationapproximating the forces applied during wear. As can be seen from thedrawing, the extensible back waist feature 32 extends in the same manneras described with respect to FIG. 3. However, due to the extensibilityof the leg flap panels 1831 and the greater extensibility of the frontwaist panel 1843, the front waist region of the diaper also tends toflare out. Thus, the diaper 1820 provides an hourglass shape-type fitwithout the added and the wasted material required for an hourglassshaped diaper. The elastic strands 54 of the leg cuffs 30 are shown tocurve in the front waist to provide a cuff that better conforms to theupper thighs of the wearer. In effect, curved elasticization is achievedwith a rectangular diaper. (It should be noted that if the leg cuffcomprises a barrier cuff as is described in the above-referenced U.S.Pat. No. 4,695,278 (Lawson), the barrier cuff will also curve andprovide better fit.)

FIG. 20 shows an alternative embodiment of a diaper 2020 of the presentinvention. The diaper 2020 has a generally hourglass shape rather thanthe T-shape previously discussed. The hourglass shape has a leg cutoutin the crotch region of the diaper to provide fit about the legs. Theextensible back waist feature 32 is similar to the extensible back waistfeature described with respect to the T-diaper except for the shape ofeach panel. Further, in this embodiment, the absorbent core 28 extendsinto a portion of the hip panel 38. In an especially preferredembodiment, the absorbent core 28 is not joined to the hip panel 38 suchthat it is allowed to "float" in the hip panel 38. The absorbent corethus provides stiffness in a portion of the hip panel to preventbunching of the hip panel. The extensible front waist feature 2042preferably has a pentagon shape such as is described in U.S. Pat. No.5,151,092 (Buell, et al.). In the embodiment shown in FIG. 20, theextensible front waist feature 2042 comprises a SELF web of the presentinvention wherein the extensibility of the SELF web is in a pentagonshape due to the nonextensible chevron-shaped landing member,reinforcing strip 2041, being joined over a portion of the SELF web. Theclosure system for the diaper is preferably the dual tension fasteningsystem described hereinafter providing an angled line of tension aboutthe wearer. The dual tension fastening system comprise a primaryfastening system and preferably a waist closure system. As shown in FIG.20, the tape tabs 2040 of the primary fastening system are disposed atan angle to the lateral direction to provide such an angled line offastening. The diaper 2020 is also provided with a waist closure systemincluding a pair of first attachment components 2002 longitudinallyaligned with the extensible front waist feature 2042 to provide tensionthrough the extensible front waist feature and a second attachmentcomponent (not shown) comprising a portion of the topsheet 24.

The closure system anchors the diaper about the wearer throughout thediapers use so the diaper has a reduced likelihood to sag/gap andslide/slip during use. The closure system is designed to create a lineor zone of tension causing a hoop force connecting the lumbar curve ofthe back over the hips to under the abdominal crease to form theanchoring function. This line or lines (zone) of tension (hereinafter,the primary line of tension) is disposed substantially about theperimeter of the low motion zone of the wearer to impart anchoringforces that maintain the position of the diaper throughout wearing. Theprimary line of tension is preferably disposed at an angle to thehorizontal on the body of the wearer (at an angle to the lateraldirection of the diaper) such that the primary line of tension extendsfrom around the lumbar curve (the small of the back) over the iliaccrest of the hips to the front of the wearer, preferably below the lineof the abdominal crease. Thus, the primary line of tension is disposedin the zone of minimal changing body dimension, a sustained wearingposition (i.e., the primary line of tension is not disposed over theabdomen of the glutens maximus which increase and decrease in dimensionduring movement), such that the primary line of tension stabilizes andmaintains anchoring forces which maintaining the position of the diaperon the wearer such that diaper is unlikely to slide or slip downwardduring the entire time of use due to the movement of the wearer or tothe force of the increased weight of the diaper when it is loaded. Theangled primary line of tension created by the closure system alsoimparts an upward anchoring force on the diaper tending to pull thediaper up on the body, and thus counteract the weight force of theloaded diaper, since the primary fine of tension has a vector componentin the longitudinal direction. The normal anchoring force is created bythe primary line of tension (another vector component of the angledprimary line of tension) anchoring the diaper, particularly theabsorbent core, in the low motion zone since the normal anchoring forcesact compressively to push the absorbent core toward the body. Thesenormal anchoring forces thus assist in maintaining the fit of the diaperas well as reducing leakage since the absorbent core is maintained inclose relationship with the body. The angled primary fine of tensionalso tends to reduce red marking since the anchoring forces are disposedin the low motion zone such that the body dimension is not increasing ordecreasing along the primary line of tension which could cause redmarking.

Since the primary line of tension is to be disposed at an angle to thelateral direction to provide its anchoring function, the closure systemis designed to provide an angled closure mechanism to insure such aprimary line of tension is imparted to the diaper. The closure systemmay thus comprise a number of different fastening systems for providingan angled primary line of tension. For example, the closure system maysimply comprise a primary fastening system. The closure system mayadditionally anchor a portion of the extensible front waist feature,and, if desired, a portion of the leg cuff.

For the closure system shown in FIG. 20, each securement member of theclosure system preferably comprises a tape tab 2040 capable of beingsecured to a landing member, preferably reinforcing strip 2041, so as toprovide a primary line of tension through the diaper at an angle to thelateral direction. Thus, the tape tab is generally shaped and orientedto allow the tape tab to engage the landing member so as to provide aprimary line of tension at an angle to the lateral direction, preferablythrough the diaper substantially about the low motion zone. In theembodiment shown in FIG. 20, the tape tab 2040 is joined to the sidepanel 36 at an angle to the lateral direction to provide the angledprimary tension line desired. For example, a rectangular tape tab suchas known in the art or a tape tab having any other shape may be rotatedwith respect to the lateral direction when applied to the diaper suchthat the tape tab is disposed at an angle to the lateral direction ofpreferably between about 5° to about 30°, preferably from about 15° toabout 20°.

An alternative embodiment of the tape tab may have the tab portionshaped and oriented at an angle to the lateral direction to insure theformation of the primary line of tension at an angle to the lateraldirection. Most preferably, the sidelong edges of the tape tabs arecurved to allow angled taping in order to follow the shape/build of thewearer, to create the angled primary line of tension about the lowmotion zone to anchor the diaper on the wearer, and to allow thediaperer to conveniently apply the tab portion on the landing member soas to accommodate the diaper design. Further, the curved shape of thesidelong edges of the tab portion allows high tape placement in the backwaist region yet allows low tape placement on the landing member tominimize marking of the stomach, hips and legs of the wearer to improvethe comfort of the diaper for the wearer. The tab portion alsoaccommodates the leg of the wearer in that if the tape tab waspositioned too low on the product, marking could occur on the legs ofthe wearer which would negatively impact comfort and fit. An example ofsuch a tape tab design is disclosed in U.S. patent application Ser. No.08/072,300, "Absorbent Articles Providing Sustained Dynamic Fit" filedby LaVon, et al. on Jun. 3, 1993, which patent application isincorporated herein by reference.

The landing member can also assume varying sizes and shapes to providethe angled primary line of tension. In a preferred embodiment asillustrated in FIG. 20, the landing member comprises a reinforcing strip2041 having a chevron shape so as to create the angled primary line oftension of the present invention. The reinforcing strip 2041 is alsopreferably provided with indicia means 2004 for aiding the diaper andfiring the diaper to a wearer to obtain optimal waist fit and legopening fit. The indicia means 2004 are preferably disposed in rowsdisposed at an angle to the lateral direction, preferably at the sameangle as the tape tabs 2040, to allow angled fastening of the tape tabfor optimized fit and for providing an angled primary line of tension.(In an alternative configuration, the landing member can be extensible,for example--formed from a SELF web comprising a nonwoven material, toallow the front waist region to expand even more to accommodate thegrowth of the wearer's stomach.)

As shown in FIG. 20, the closure system preferably additionallycomprises a waist closure system that anchors a span of the front waistpanel 43, preferably the extensible front waist feature 2042. Such awaist closure system is disclosed in the above-referenced U.S. patentapplication Ser. No. 08/072,300 (La Von, et al.) and U.S. Pat. No.5,242,436 (Weil, et al.). Alternatively, the components of the waistclosure system can also be configured to provide an angled line oftension (e.g., the first attachment components may be joined at an angleto the lateral direction).

FIG. 21 shows a further alternative embodiment of an extensible frontwaist feature 2142 of the present invention. The front waist panel 2143has a central waistband panel 2100 and a pair of ear panels 2102disposed on either lateral side of the central waistband panel 2100. Thecentral waistband panel 2100 preferably comprises a stretch laminate,more preferably a zero strain stretch laminate, such as are described inabove-referenced U.S. Pat. No. 5,151,092. The central waistband panel2100 thus comprises a portion of the topsheet 24, a portion of thebacksheet 26, and an elastomeric member 2104 positioned between thetopsheet 24 and the backsheet 26, all of which have been mechanicallystretched. (It should be noted that the central waistband panel has alsobeen passed through the SELF process; however, the bands and pleats havenot been shown in the drawing for simplicity purposes.) The ear panels2102 each comprise a SELF web to further enhance the stretchability andextensibility of the extensible front waist feature 2142. Each ear panelSELF web is similar to the SELF webs described with respect to use forany of the panels of the back waist feature 32. This provides ease ofmanufacture since the ear panel SELF webs can be formed simultaneouslywith the central waistband panel 34 of the extensible back waist future32 of the previous diaper during continuous manufacture. Further, forease of manufacture, the central waistband panel 34 of the back waistfuture 32 may alternatively comprise a stretch laminate, preferably azero strain stretch laminate, so that the same piece of elastic materialmay form the elastomeric member forming both central waistband panels.The primary fastening system of the closure system comprises a landingmember comprising a reinforcing strip 2041 having a chevron shape. Theclosure system additionally comprises a waist closure system, includingthe first attachment components 2106, for providing tension through theextensible front waist feature 2142.

FIG. 22 shows a further alternative embodiment of an extensible frontwaist feature 2242 of the present invention. The front waist panel 2243comprises a central waistband panel 2200, a tummy panel 2204, and a pairof ear panels 2202. The central waistband panel 2200 is preferably azero strain stretch laminate as described herein with respect to FIG.21. The ear panels 2202 are also similar to the ear panels 2102 shown inFIG. 21. The tummy panel 2204 extends longitudinally inwardly from thecentral waistband panel 2200 and comprises a SELF web. The SELF web ofthe tummy panel 2204 can be the same or similar to the SELF web of theear panels or it can have less extension forces than the ear panels.

FIG. 23 shows another alternative embodiment of an extensible frontwaist feature 2342 of the present invention. The front waist panel 2343comprises a central waistband panel 2300, a tummy panel 2304, and a pairof ear panels 2302 on either longitudinal side of the central waistbandpanel 2300. In this embodiment, the tummy panel 2304 comprises a stretchlaminate, preferably a zero strain stretch laminate, comprising anelastomeric member 2104. The central waistband panel 2300 and the earpanels 2302 each preferably comprise a SELF web. The central waistbandpanel 2300 extends longitudinally inwardly from the end edge 48 fromabout 6 mm to about 25 mm, preferably about 12 mm. The force/extensionproperties of each SELF web may be the same or be different dependingupon the desired extensibility of each panel. In the embodiment shown inFIG. 23, each of the SELF webs preferably has the same extension forceproperties. This front waist feature 2342 thus has a "SELF window." Thisfront waist feature thus reduces sagging since there is no elasticadjacent the end edges to pull down the waist. On an alternativeembodiment of this configuration, the extensible back waist feature mayhave arcuate shape or angled to the lateral direction bands and pleatsfor the SELF webs to provide force resolution and extensibility at anangle to the lateral direction.

FIG. 24 shows a further alternative embodiment of an extensible frontwaist feature 2442 of the present invention. The front waist panel 2443comprises a central waistband panel 2400, a pair of ear panels 2402, arummy panel 2406, and a landing panel 2408. The central waistband panel2400 comprises a stretch laminate, preferably a zero strain stretchlaminate comprising an elastomeric member 2104. The ear panels 2402, thetummy panel 2406, and the landing panel 2408 each comprise a SELF web.The landing panel 2408 extends longitudinally inwardly from andpreferably beyond the landing member of the primary fastening system. Asshown in FIG. 24, the landing member comprises a pair of reinforcingstrips 2441 laterally spaced from each other and positioned on thediaper at an angle to the lateral direction. The landing panel SELF webis laterally bounded by the reinforcing strips 2441 to provide stretchand extensibility between the reinforcing strips 2441.

Test Methods

Surface-Pathlength

Pathlength measurements of formed material regions are to be determinedby selecting and preparing representative samples of each distinctregion and analyzing these samples by means of microscopic imageanalysis methods.

Samples are to be selected so as to be representative of each region'ssurface geometry. Generally, the transition regions should be avoidedsince they would normally contain features of both the first and secondregions. The sample to be measured is cut and separated from the regionof interest. The "measured edge" is to be cut parallel to a specifiedaxis of elongation interest. Usually this axis is parallel to the formedprimary-axis of either the first region or the second region. Anunstrained sample length of one-half inch is to he "gauge marked"perpendicular to the "measured edge": while attached to the webmaterial, and then accurately cut and removed from the web material.

Measurement samples are then mounted onto the long-edge of a microscopicglass slide. The "measured edge" is to extend slightly (approximately 1mm) outward from the slide edge. A thin layer of pressure-sensitiveadhesive is applied to the glass face-edge to provide a suitable samplesupport means. For highly formed sample regions it has been founddesirable to gently extend the sample in its axial direction (withoutimposing significant force) simultaneous to facilitate contact andattachment of the sample to the slide-edge. This allows improved edgeidentification during image analysis and avoids possible "crumpled" edgeportions that require additional interpretation analysis.

Images of each sample are to be obtained as "measured edge" views takenwith the support slide "edge on" using suitable microscopic measuringmeans of sufficient quality and magnification. Data herein presented wasobtained using the following equipment; Keyence VH-6100 (20x Lens) videounit, with video-image prints made with a Sony Video printer Mavigraphunit. Video prints were image-scanned with a Hewlett Packard ScanJet IIPscanner. Image analysis was on a Macintosh IICi computer utilizing thesoftware NIH MAC Image version 1.45.

Using this equipment, a calibration image initially taken of a gridscale length of 0.500" with 0.005" increment-marks to be used forcalibration setting of the computer image analysis program. All samplesto be measured are then video-imaged and video-image printed. Next, allvideo-prints are image-scanned at 100 dpi (256-level gray scale) into asuitable Mac image-file format. Finally, each image-file (includingcalibration file) is analyzed utilizing Mac Image 1.45 computer program.All samples are measured with freehand line-measurement tool selected.Samples are measured on both side-edges and the lengths recorded. Simplefilm-like (thin & constant thickness) samples require only one end-edgeto be measured. Laminate and thick foam samples are measured on bothside-edges. Length measurement tracings are to be made along the fullgage length of cut sample. In cases of highly deformed samples, multiple(partially overlapping) images may be required to cover the entire cutsample. In these cases, select characteristic features common to bothoverlapping-images and utilize as "markers" to permit image lengthreadings to adjoin but not overlap.

The final determination of surface-pathlength for each region isobtained by averaging the lengths of five (5) separate 1/2" gage-samplesof each region. Each gage-sample "surface-pathlength" is to be theaverage of both side-edge surface pathlengths.

Poisson's Lateral Contraction Effect

The Poisson's lateral contraction effect is measured on an Instron Model1122, as available from Instron Corporation of Canton, Massachusetts,which is interfaced to a Gateway 2000 486/33 Hz computer available fromGateway 2000 of N. Sioux City, S. Dak., using Test Works™ software whichis available from Sintech, Inc. of Research Triangle Park, N.C. Allessential parameters needed for testing are input in the TestWorks™software for each test. Data collection is accomplished through acombination of manual sample width measurements, and elongationmeasurements made within TestWorks™.

The samples used for this test are 1" wide×4" long with the long axis ofthe sample cut parallel to the direction of the first region of thesample. The sample should be cut with a sharp knife or suitably sharpcutting device designed to cut a precise 1" wide sample. It is importantthat a "representative sample" should be cut so that an arearepresentative of the symmetry of the overall pattern of the deformedregion is represented. There will be cases (due to variations in eitherthe size of the deformed portion or the relative geometries of regions 1and 2 ) in which it will be necessary to cut either larger or smallersamples than is suggested herein. In this case, it is very important tonote (along with any data reported) the size of the sample, which areaof the deformed region it was taken from and preferably include aschematic of the representative area used for the sample. In general, an"aspect ratio" of (2:1) for the actual extended tensile portion (l1:w1)is to be maintained if possible. Five samples are tested.

The grips of the Instron consist of air actuated grips designed toconcentrate the entire gripping force along a single line perpendicularto the direction of testing elongation having one flat surface and anopposing face from which protrudes a half round. No slippage should bepermitted between the sample and the grips. The distance between thelines of gripping force should be 2" as measured by a steel rule heldbeside the grips. This distance will be referred to from here on as the"gauge length".

The sample is mounted in the grips with its long axis perpendicular tothe direction of applied elongation. An area representative of theoverall pattern geometry should be symmetrically centered between thegrips. The crosshead speed is set to 10 o in/min. The crosshead moves tothe specified strain (measurements are made at both 20 and 60%elongation). The width of the sample at its narrowest point (w2) ismeasured to be the nearest 0.02" using a steel rule. The elongation inthe direction of applied extension is recorded to the nearest 0.02" onthe TestWorks software. The Poisson's Lateral Contraction Effect (PLCE)is calculated using the following formula: ##EQU3## where w₂ =The widthof the sample under an applied longitudinal elongation;

w₁ =The original width of the sample;

l₂ =The length of the sample under an applied longitudinal elongation;and

l₁ =The original length of the sample (gauge length);

Measurements are made at both 20 and 60% elongation using five differentsamples for each given elongation. The PLCE at a given percentelongation is the average of five measurements.

Hysteresis Test

The hysteresis test is used for measuring the percent set and percentforce relaxation of a material. The tests are performed on an InstronModel 1122, available from Instron Corporation of Canton, Mass. which isinterfaced to a Gateway 2000 486/33 Hz computer available from Gateway2000 of N. Sioux City, S. Dak. 57049, using TestWorks™ software which isavailable from Sintech, Inc. of Research Triangle Park, N.C. 27709. Allessential parameters needed for testing are input in the TestWorks™software for each test (i.e., Crosshead Speed, Maximum percentelongation Point and Hold Times). Also, all data collection, dataanalysis and graphing are done using the TestWorks™ software.

The samples used for this test are 1" wide×4" long with the long axis ofthe sample cut parallel to the direction of maximum extensibility of thesample. The sample should be cut with a sharp exacto knife or somesuitably sharp cutting device design to cut a precise 1" wide sample.(If there is more than one direction of elongation of the material,samples should be taken parallel to representative directions ofelongation.) The sample should be cut so that an area representative ofthe symmetry of the overall pattern of the deformed region isrepresented. There will be cases (due to variations in either the sizeof the deformed portion or the relative geometries of the first andsecond regions) in which it will be necessary to cut either larger orsmaller samples than is suggested herein. In this case, it is veryimportant to note (along with any data reported) the size of the sample,which area of the deformed region it was taken from and preferablyinclude a schematic of the representative area used for the sample.Three separate tests at 20, 60 and 100% strain are typically measuredfor each material. Three samples of a given material are tested at eachpercent elongation.

The grips of the Instron consist of air actuated grips designed toconcentrate the entire gripping force along a single line perpendicularto the direction of testing stress having one fiat surface and anopposing face from which protrudes a half round to minimize slippage ofthe sample. The distance between the lines of gripping force should be2" as measured by a steel rule held beside the grips. This distance willbe referred to from hereon as the "gauge length". The sample is mountedin the grips with its long axis perpendicular to the direction ofapplied percent elongation. The crosshead speed is set to 10 in/min. Thecrosshead moves to the specified maximum percent elongation and holdsthe sample at this percent elongation for 30 seconds. After the thirtyseconds the crosshead returns to its original position (0% elongation)and remains in this position for 60 seconds. The crosshead then returnsto the same maximum percent elongation as was used in the first cycle,holds for thirty seconds and then again returns to zero.

A graph of two cycles is generated. A representative graph is shown inFIG. 7. The percent force relaxation is determined by the followingcalculation of the force date from the first cycle: ##EQU4## The percentset is the percent elongation of the sample of the second cycle wherethe sample starts to resist the elongation. The percent set and thepercent force relaxation are shown graphically also in FIGS. 7 and 15.The average percent force relaxation and percent set for three samplesis reported for each maximum percent elongation value tested.

Tensile Test

The tensile test is used for measuring extension force (force) versuspercent elongation properties and percent available stretch of amaterial. The tests are performed on an Instron Model 1122, availablefrom Instron Corporation of Canton, Mass. which is interfaced to aGateway 2000 486/33 Hz computer available from Gateway 2000 of N. SiouxCity, S. Dak., using TestWorks™ software which is available fromSintech, Inc. of Research Triangle Park, North Carolina. All essentialparameters needed for testing are input in the TestWorks™ software foreach test. Also, all data collection, data analysis and graphing aredone using the TestWorks™ software.

The samples used for this test are 1" wide×4" long with the long axis ofthe sample cut parallel to the direction of maximum extensibility of thesample. The sample should be cut with a sharp exacto knife or somesuitably sharp cutting device designed to cut a precise 1" wide sample.(If there is more than one direction of extensibility of the material,samples should be taken parallel to a representative direction ofelongation). The sample should be cut so that an area representative ofthe symmetry of the overall pattern of the deformed region isrepresented. There will be cases (due to variations in either the sizeof the deformed portion or the relative geometries of the first andsecond regions) in which it will be necessary to cut either larger orsmaller samples than is suggested herein. In this case, it is veryimportant to note (along with any data reported) the size of the sample,which area of the deformed region it was taken from and preferablyinclude a schematic of the representative area used for the sample.Three samples of a given material are tested.

The grips of the Insiron consist of air actuated grips designed toconcentrate the entire gripping force along a single line perpendicularto the direction of testing stress having one fiat surface and anopposing face from which protrudes a half round to minimize slippage ofthe sample. The distance between the lines of gripping force should be2" as measured by a steel rule held beside the grips. This distance willbe referred to from hereon as the "gauge length". The sample is mountedin the grips with its long axis perpendicular to the direction ofapplied percent elongation. The crosshead speed is set to 10 in/min. Thecrosshead elongates the sample until the sample breaks at which pointthe crosshead stops and returns to its original position (0%elongation).

The percent available stretch is the point at which there is aninflection in the force-elongation curve, beyond which point there is arapid increase in the amount of force required to elongate the samplefurther. The average of the percent available stretch for three samplesis recorded.

While the test methods described above are useful for many of the webmaterials of the present invention it is recognized that the testmethods may have to be modified to accommodate some of the more complexweb materials within the scope of the present invention.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An disposable absorbent article having a frontwaist region and a back waist region, the absorbent article comprising:achassis assembly comprising a liquid pervious top sheet, a liquidimpervious backsheet joined with said topsheet, and an absorbent corepositioned between said topsheet and said backsheet; a pair ofextensible leg cuffs, each extensible leg cuff comprising a leg flappanel joined to and extending laterally outwardly from said chassisassembly, said leg flap panel being extensible in the lateral directionallowing said leg flap panel to expand in the lateral direction toprovide additional void volume; and an extensible back waist featurepositioned in said back waist region, said extensible back waist featurejoined to an extending longitudinally outwardly from said chassisassembly, said extensible back waist feature comprising:(a) a hip panelextending longitudinally outwardly from said absorbent core, said hippanel being extensible in a direction having vector component in thelateral direction; (b) a central waistband panel joined to and extendinglongitudinally outwardly from said hip panel, said central waistbandpanel being extensible in a direction having a vector component in thelateral direction, the extension force of said central waistband panelbeing greater than the extension force of said hip panel; and (c) a pairof side panels joined to and extending laterally outwardly from saidcentral waistband panel and at least a portion of said hip panel, eachsaid side panel being extensible in a direction having a vectorcomponent in the lateral direction.
 2. The absorbent article of claim 1additionally comprising at least one elastic member operatively joinedwith each said leg flap panel.
 3. The absorbent article of claim 1wherein an end of each said elastic member extends longitudinally intosaid hip panel.
 4. The absorbent article of claim 3 wherein each saidside panel has a waist edge and a leg edge, and said hip panel extendslongitudinally inwardly from said leg edge of each said side panel. 5.The absorbent article of claim 4 wherein said end of each said elasticmember is operatively joined to said leg flap panel adjacent said legedge of said side panel.
 6. The absorbent article of claim 1 whereinsaid central waistband panel and each said side panel comprise astructural elastic-like film web.
 7. The absorbent article of claim 1wherein said extensible front waist panel comprises a structuralelastic-like film web.
 8. The absorbent article of claim 1 wherein eachsaid leg flap panel comprises a structural elastic-like film web.
 9. Theabsorbent article of claim 1 wherein said chassis assembly comprises astructural elastic-like film web.
 10. The absorbent article of claim 1wherein each said leg cuff additionally comprises a barrier leg cuffjoined to said topsheet.